When you described the fainting spell you first had, it sounded to me like a panic attack. I had one in my C office. It was weird and I though I was having a heart attack, and I nearly passed out. I have had fainting spells once in a great while since I was about 16. It's embarrassing in public, but unless your heart is having problems, you are probably all right. Dehydration can also cause your BP to lower, and you can faint.

Anyway, your H seems to be keeping you on the hook. What do you think he wants for the future? Is it maybe if he doesn't get a D from you, he can tell ow he can't M her? You said friends told you he was acting like a Don Juan a few years ago. That he may not have had only one ow in the past. What do you believe he will eventually do? Do you want him back the way he is? Would he want to come back to you the way you are?
You are making yourself sick and miserable staying like this. I am not saying for you to file for a D. I think you could put that aside for now, and just work on you. You need therapy really badly. Someone not to talk to just about your H and M, but intensive with you about what you are doing to your spirit, hurting who you are inside. You can't go on like this forever. Have you finished school yet? Will you be able to support yourself if you have to? You said you have some sort of disability? Will that interfere with your ability to support yourself and your S?
Have a nice evening, I hope your S is enjoying his senior year.
vc crazy