My father is in the ICU with heart failure and COPD and I fear it's the end. How do I cope with all this guilt and sadness?

My dad has had end stage COPD since 2015 and lived with me this whole time. I've been through numerous hospital and ICU stays with him and a few times he was even on the vent. All that to say this time feels different. I am so terrified this is the end because he just seems so weak and tired and his body just seems like it can't take much more. He was brought in via ambulance because he couldn't breath and thought he was having a heart attack. They did a heart cath and told me he's in severe heart failure with 15% heart function. He ended up in ICU on a bipap. The next morning he seemed quite a bit better and even the day after that he seemed as if he was headed towards recovery but as soon as they moved him out of ICU he started to nosedive. He got worse over the next 4 to 5 days and now he's back in ICU. I went from having hope because it looked like it was getting better to being terrified this is it. I'm just so scared because him and I had a close bond while I was growing up and young adult. It wasn't until he got diagnosed with COPD and had to move in with my husband and I that my relationship with him went south due to me not being able to cope with some things he did and didn't do as a single father growing up but also because I don't think I could truly accept he had an irreversible disease...I took my anger and frustration out on him many times and said hurtful things and I've felt guilty over it before but now the guilt is really building up and I'm just full of regret and angry at myself that my dad may be leaving this world soon and that's how I treated him. I feel like the worst daughter ever. I've been with him almost every day he's been in there. I'll hold his hand and try to talk but most of the time he's too tired to talk or doesn't say much and the guilt just eats at me. I cry while he sleeps because I feel so awful but also scared because the reality of my daddy not being here soon is setting in. I want to say I'm sorry but anytime I bring up anything remotely personal or emotional he gets worked up and that's not good for his heart right now. He's in heart failure but also dealing with tachycardia and very low blood pressure so I don't want to stress him out. What do I do? Bring it up or leave it unsaid? I feel like I'm bothering him too much lately because I'm struggling emotionally and yearning for closure all the while forgetting that he's going through a lot and his body is very weak and when I step back from myself and recognize his physical and emotional state I question if I should even bring any of this up because it's probably too upsetting for him and the last thing I want to do is make this worse on him. I'm sorry this is so long. I'm just scared to lose him and I took for granted all the opportunities I had to make things better with him. I just hope he knows when he leave s this world how much I really loved him.