I just turned 57 yesterday. My parents are in their 70s and very difficult. My mom still treats me like a kid and tries to be very controlling. How can I deal with this?

I think you may be and hope you are seeing a therapist for your mental health issues. Has that therapist suggested to you that you and Mom may be stuck in a habitual way of interacting, that you may depend upon one another too much and see too much of one another. Ultimately your Mom may be correct, that you should not see one another.
It takes, at BEST a long time for Moms and daughters, in my experience and my opinion to see one another as human beings, with flaws, limitations, and love. To see that it can't all be a fairy tale movie. I still recall looking at the lines around my daughter's eyes (she is 60 this month) and thinking "Hey, you might need to get it that your daughter is a grown woman, not a child". She and I have developed a wonderful friendship in the last few years, one in which every word doesn't have the weight of heavy luggage of expectations, of limitations. I treasure it. So know that there is still hope. But that hope rests as much in your not taking so seriously what Mom says, as it does in what Mom says. When she gives direction and criticism practice saying "Thanks, Mom; I love your input; I promise you I will think about what you said. I know you love me and have my best interests in your heart."
Try to branch out. You cannot imagine the relief of knowing you are NOT alone; there are so many others trying to hide what they try daily to survive and deal with.
My heart goes out to you. Here am I with all this advice, right? Mostly I just want to say know that there is hope. Use your therapist. Try to find support groups and those you can discuss these things with without having the weight of familial expectations there. Understand your Mom is flawed and frustrated, but she loves you and is doing the best she can with her own limitations.
Good luck to you.

Is it because of your mental problems they feel they need to controll you? Are your problems lifelong like Bi-Polar. I have a cousin who suffers from Bi-Polar and is a retired teacher. And believe me, no one ever controlled him.

How do they try to control you? Do you tend to tell them too much about your life? Maybe time to back away. As Mom said, you stay in ur house and they stay in theirs. Really if I had parents, or anyone for that matter, that did nothing but put me down and try control me, I would have been gone long ago. Just because she is ur parent doesn't mean you put up with it. You are now an adult and and need the respect.

So take a long break for now. Evaluate who you are and how to improve on that. Seems you are independent since you have your own place. So you work. My worked helped define me because I was good at it. Maybe you need to realize that your parents will never be who you would like them to be. Excepting that they will never love u they way you want them to. Except you for who you are not what they want u to be. You are not the only person with parents like these. Stay on the forum and you will see that.

My GF married at 19 to pretty much get away from Mom. Her DH was drafted not long after the wedding and spent 2 years in the service. They had 2 boys a yr apart. They were toddlers when GF and husband found a house they liked and bought. First thing out of Moms mouth was why did they not get her approval before buying the house. What!

Read Boundries by Townsend and Cloud.

Are you your parents' caregiver? It seems like you shouldn't be.

i think Beatty has good advice, if you can hang out with other people would it help?
Would some calming hobbies help too? I try crossstitch and reading

Are there other people you like to hang out with too?

Would spending less time with Mom & more time with other people help?