@MARRY IRFAN,
5 years is a long time for a guy to feel that he can keep you there, so no one else can have you and play the field as well.
People need to earn our trust love. You don't just give it out. It's those types of people that you give and give to, that will take advantage.
This is what he did. And, obviously he "thinks" he has feelings for this other girl now but how disrespectful of him to treat you like that at Uni.
Don't worry about what other people think. You hold your head up high, learn from this, not to give out all your trust and love until it is shown back to you and be happy because honestly? He is someone you would not have wanted to marry imagine the heartache 10 years into the relationship with children involved. He will cheat on her eventually.
Also don't feel so bad about the sex thing - see it for what it was, "he's a loser" user. So now you 100% know, instead of 90%.. When you walk past him, look through him as if he does not exist. Smile around people when he's around so he sees you are free and happy, it will eat at him, he will try to communicate with you, ignore him, don't answer any calls/text messages, see him for who he is. But you will get the last laugh if you do this as it will eat at him...
As for your condition, sorry to hear about that, that must bring you down and make you feel horrid at times, maybe even depressed.
Try to resolve it, don't give up and also know everyone has something wrong with them, you're not alone.
Chin up and get into the fighting spirit. . That being 'YOU' deserve better, you know it, you've learnt from this and that, next time you will find someone who you can trust visa versa that loves you visa versa... And, don't give up what ever it is you are studying, because you will succeed in your life with that choice, be who you want to be in life and go for it.