A rant on how my life turned to shit on Easter

Ok, so I know that it has been a while since Easter, but I also thought I could handle everything myself. And I did up until a few weeks ago when I've started having anxiety attacks. So I'm gonna rant here. And if anyone has any advice, I'll appreciate it. I need a different point of view.I had been dating this guy (named for purpose of anonymity) named Drake for 3 years. I had been going on dates with him, talking to him. We even lived with each other for about 7 months. I had thought things were going to last, so I spent a whole paycheck to buy him a ring and propose to him. And things lasted pretty good over the next year until the beginning of this year, really.At that time, Drake thought that it would be a good idea to work 15 hours a day at school, which he said was fine cause he said it would be for a couple weeks then things would settle down. Jump from January to mid March, a couple weeks past when he said he'd have more free time , and he was still working 15 hours a day for school. I, thinking I could help distract him, over this whole time, tried to plan a weekend date for almost every weekend, and every weekend he came up with some excuse. Which was fine. School was more important than me. Until Drake started talking about almost passing out and falling down stairs and getting random nosebleeds from working too much. So I told him he should come with me to Easter! I gave him 2 weeks notice. He said he would come. Then on Easter Day when I asked if I could come pick him up. No answer. He didn't answer me until 10 o clock that night, saying he chose to work on homework instead.I felt like I needed to reach out and try to help him. I didn't want him to be suffering this much. Not when I knew how much pain he had endured over the semester. So I told him he should talk to his teachers and explain how much he was working each day so that maybe he could try to get more time to eat properly, to sleep more, to relax and have some fun. I knew that if he talked to them, he would no longer be going through this pain.He read my message. But gave me no response. I sighed knowing he probably moved on to work on something else. Then right before I fell asleep that night, he sends me this big text saying how he did not like the advice I was giving him and that we should be just friends, saying how he sees no way to try and make us work anymore. I was in shock. I was tearing up. This came out of left field, and all because I was trying to help.I cried that entire night, and cried myself to sleep. Then I went through the whole grieving problem, ending with me finding out he had cheated on me with several guys over the last year, created a dating profile with MY ENGAGEMENT RING I GAVE HIM ON HIS FINGER, and that he was already seeing a new guy behind my back. I was pissed. I confronted him on all these things. He denied them all. I had the fucking proof under his nose, and he denied them. That was last week.Ever since then, right before bed, I keep thinking that I must have done something wrong. I must not have tried hard enough, maybe I tried to hard. Maybe I was too ugly for him, or my personality is too dull. These thoughts keep swirling my head, my breathing speeds up, and I cry. A lot. Three nights ago, I had a panic attack that almost made me pass out where I felt like I was drowning. And now I don't know what to do. I really just want someone to talk to but all my friends are too busy.Sorry for the long post and thank you to all who read through this. Feel free to message me anything, or to give me advice so I can move on from this.