In need of relationship/breakup advice

Warning! Kind of long, confusing story.....

So I am 17 and so is my “boyfriend”. We have been dating for about 5 months or so. We spend a lot of time together, I basically live over at his place. I am out of school (so is he) and I’m also looking for a job, so as you can tell I never get to leave home a lot, and that bugs the crap out of me. With him always being home with me and only working 2-3 days a week I just started to feel smothered. I would try to go back to my place but he says he doesn’t trust me and he would always have to come with me. He always gets mad if a guy text me, which is very rare. Yet he can be snap chatting like 10 girls and it’s supposed to be ok cause I’m supposed to trust him, which I do, but it’s just not right. I personally don’t think it’s right... anyways I kind of think he just pushed me away kind of a lot, by smothering me. I still love and care about him, but I don’t want to be with him anymore. I have already tried to call it off with him, and he was just crying me a river. He also said he wouldn’t let it happen because he knows I love him and it shouldn’t happen. I tried to explain to him tho how I felt and he would just not listen... so he says what is going on is us having a break, but I want to say it’s us being over... now I would get mean and aggressive because obviously being kind and firm isn’t doing the trick, but here is where the hard part comes in. So he had been having some issues with his left side for a while and he finally got it checked out. Turns out his heart is in really bad condition. And if he can’t fix his heart himself within this next week (by being on a better diet) then he will have to have heart surgery. He is really scared he is going to die so young, and it’s a possibility he might. He keeps telling me how much he loves me and wants to have a family with me, but I just don’t feel the same anymore..... so my question to everyone out here is what the hell should I do? Should I get mean and aggressive? Should I just keep telling him over and over? Should I just play along with it until he’s better? (Which can take a long while)... anyways tell me what you think I should do in the comments. Thank you, and sorry it’s so long.