3 months is not that long of a time to get over someone, unless you don't have a conscience. Give it sometime. I can feel that you feel unjustified, betrayed so to speak. Those hurt for awhile. It's too easy to blame oneself. Well, it's their loss!

Get out, take a walk. Go to the pub. Re enter life somehow. Get out of your head. You'll feel better.

Hope you get to feeling better hun.