My husband's family doesn't like me because of lies my adult stepson has told them. I am dreading the aftermath of losing my husband. What should I do?

Say nothing until your husband passes. If you can, purchase a preburial. When the time comes do what your deceased husband wanted. You are the next of kin and they cannot override your burial decision. They can always have an after the fact defacto funeral at their own expense.

Well, by "anything happening" to his father your stepson doesn't mean what becomes of his father's remains, does he. He means if any harm comes to his father while his father is still alive.

I'm sorry that you're worried, especially at what must be a stressful time anyway. Stepfamilies can be very difficult things to negotiate. Did your husband make a will, or put anything in writing about his funeral preferences? If he didn't, you decide on the funeral arrangements, keeping it as simple as you believe your husband would have wished, and you inform anyone with an obvious right to know - such as his son - what the arrangements are. That is the correct thing to do. Do you have friends or family of your own supporting you through this?

A priority right now is to make sure he has all his legal protections in place so that his family can't descend upon you like flying monkeys during any illness or after his passing. He needs to assign you as his DPoA, make an Advance Healthcare Directive and a Last Will with an attorney so that it is legally unimpeachable and there is peace of mind and protection. You must also do this for yourself, since you should never assume that you'll remain healthy -- many a spouse/caregiver has become ill in tandem with their LO. Some even pass before them. At the very least you should video him expressing his wishes, but this is not the same as going through an attorney because there is no "proof" he's in his right mind or isn't being pressured.

As to whether you should tell his children...if he wants this he himself should tell them but be forewarned that if he is slipping into dementia he may start saying things to people that are incorrect or delusional. If you think he's not able to make the decision to tell them, then if you are his PoA you do what is in his best interests but only tell them after all the legal documents are in place. I wish you both peace in your hearts.

You owe them nothing! Follow your husband’s wishes and don’t worry about what they have to say. Why do you care? They have no jurisdiction over you or your husband. Do exactly as you want and if it’s going to save you aggravation don’t contact them until after it’s taken care of. Hold your head high you did nothing wrong. Good luck to you. You have enough to worry about and enough on your plate with a sick husband, you don’t need to worry about the wackos💜

Did your husband write his wishes down?
Can a conversation be recorded with him explaining what he wants as far as a funeral (or no funeral)?
Does your husbands family know that he is now sick? And if so how sick he is?
You do not mention a diagnosis in your profile and just mention that "his mind is no longer shape"
It might be time to let his children know what is going on, it is amazing when faced with a diagnosis sometimes even hard hearts are softened a bit and closed minds may open a bit.

Hello. See a lawyer ... or several lawyers. And the bank. And aging care counselors. See pastors and ministers from a church. And the doctor(s).

see every entity that can help make sure that when the time comes that you have all the paperwork and witnesses you need that both of you have spoken to that will back you up.

leave no questions unanswered.

you have been warned by the stepson. Be quietly prepared. Protect yourself in order to help your husband know you will care for him and his wishes.

I suspect, since there has been no love lost with your step family, that you will have little connection with them after your husband dies.
Let me ask you this, other than the step son, who you need not discuss with that family at all, have YOU yourself reached out to his family? Have you sent notes and updates as time has gone on about your husband's condition, about his wishes. When he was more well was he in contact with them? Did he love them?
My answer depends on your answers to those questions. If your husband loved them, saw them, joked and laughed with them, had celebrations with them, then I would keep the family updated. I would ask them:
"What do you prefer? I can communicate with one of you, and you can form a phone tree, or I can send you each a copy of what is going on. I know on some level he won't know who you are, but you can visit: I am pretty busy, but can muster up some tea".
If the family is not currently visiting or seeing your hubby, I cannot imagine why they would want to when he is dead, in all truth. If they are, it may be time to tell them you have an uncomfortable subject,and that is to tell them that he, sadly, asked for cremation without services.
My partner and that want that and have discussed that with our families and put it in our Trust, so there is no surprise there.
What SHOULD have been done in the past cannot now be done in the right order. But there is still time.
And, after all is said and done, if a family who hates you moves on muttering about you, so WHAT? Nothing is changed. They didn't like you then, they don't like you now, and they won't like you in the future. Continue on with your life, make new friends, and celebrate what it is to live.
My heart goes out to you and I wish you the best. My partner raised two children and I raised two children and we all love one another. We have been terribly lucky in that. But we discuss things with all, we write out things that need to be written, and face the fact that, in our 80s now, one of us will be leaving the other. I hope we keep out "step families in that loss, but there are no guarantees. My best out to you.

My mother's good friend had a similar situation to yours. She was happily married to her husband (was a second marriage for both and they had no kids together) for over 20 years then he died. His children were right there with their hands out before their father's coffin was even in the ground.
What she did was sell their house and she moved to a lovely condo. She did not tell any of his kids anything because they were not owed an explanation. Everything this couple had they got together. Their home, the cars, everything. She was her husband's heir and that was fair.
She gave him a nice funeral and then severed all ties and communication with his adult kids.
There is absolutely nothing your stepson can do. Let him call the police when his father passes. They will laugh in his face.
If he gets too cute with the threats, get a restraining order against him.
You are legally married to your husband and this means you are his next of kin. If you decide to go with cremation, that is your right. If it is your husband's wishes that there be no funeral service, don't do one. If you choose to speak to his family if they ask, tell them it that these were his wished and you're honoring them.
You don't have to answer to anyone.

If it's not too late for him to sign legal papers, have him execute a living will with his advance medical directives and funeral wishes. It also would be safer for you if you have power of attorney for his medical and legal matters. It sounds like he also needs to have a will, if he has relatives the way you describe them. But if his mind is not good, it may be too late. Get connected to a local social worker who can advise you on getting these legal papers at this point. The social worker may be able to get you connected with a pro bono attorney, if needed. Good luck!

Edit: Prayers for your husband.💗