Dad is so unsupportive

That is really hard, unfortunately we can not make decisions for others to be healthy. Try sitting down and talking to him, about your concerns for yourself, but also him. Let him know how much the heart attack scared you, and how you felt about the fear of loosing him. He may or may not be able to get it. I applaud you for taking responsibility to be more healthy, that is a big thing for someone your age. I understand, where you are coming from, I am probably your dad's age, but my husband, is the one unwilling to make a change, he kind of rolls his eyes, when I try to talk to him about being more healthy. Do the best you can, keep talking to him, let him know you love him as he is, and maybe one day he will decide he wants to be healthier. Good luck, hang in there.

Unfortunately, you can't make him want to change. No one can do that for anyone else. All you can do is look after yourself, and continue to be there for him, helping and supporting him, if/when he decides to change. Sit down and have a serious conversation with him about him making unhealthy food for you and your mom. People do things for lots of different reasons (sometimes fear, sometimes people just aren't on the same page), but if he is seriously trying to sabotage you, and he continues, then just don't eat the food he makes. Agree that either only you and your mom will cook, or when he cooks, make something separate for yourself.

Try to let go of the feeling of responsibility for making him healthy. It's very hard to watch someone you love hurt themselves with their behaviour, but he's an adult, and it's not up to you to fix him. Try not to take his reluctance to be healthy personally, and turn to your mom for the support you need, as it sounds like she is behind you.

ETA: obviously, this response makes more sense in reply to your deleted OP.