Most Helpful Guy
Forget his explanation. He cheated with several different women because he wanted to fuck them. It has nothing to do with any insecurities about himself. He wanted to fuck them and then you gave him another chance so he did it again. Predictable! He is not going to change. The sooner you get out, the quicker you will get over it.
Most Helpful Girl
Well keep telling yourself what a asshole he is. Yeah sure, other girls may get to sleep with him, but that doesn't mean he isn't a asshole and will just do to other girls what he did to you. I get that it hurts but you are truly better off without him and when you meet another guy you click with, you'll see and understand why it didn't work out. I promise with time, it will get better. Emotions are naturally high when it is recent, anyone who has been dumped can vouch for that. So accept that it will such and be shitty at the start but there will come a day when you'll be over it and thankful that it didn't work out. Him cheating is not a reflection of you.