I'm sorry you are going through this. Been there as well...
I agree with Open.. Revenge is not worth it. It will accomplish nothing. You could put on your James Bond 007 cap and look for more but in my opinion you're going to find it. Sometimes looking down into the rabit hole is not worth it. Why subject yourself to that? It won't answer your questions or relieve the pain. You found out, you know he is cheating and lying...and obviousely hurting you emotionally. I wouldn't even give him the opportunity to explain himself or turn it around on you. It's about him not you. Take care of yourself and don't take it personally.
If you're living with him I would plan a silent escape as to avoid drama and give him the opportunity to turn things back on you.
Leave before it turns ugly and gets really twisted.
I know it hurts-betrayals of trust do. Take care of yourself, be kind to yourself, and love yourself. It's hard to do...
Wishing you well.