How to get over being cheated on

I took my boyfriend back fairly quickly after finding out he cheated twice. I know i can forgive but certainly havn't forgotten. I dont know whether to give him a second chance.He seems sorry and said opportunity just got the better of him while he was away travelling for a long time. Although my friends think i'm doing the wrong thing ( and i understand why) I'm finding it too hard to let go. i still think hes the one i can see myself spending my life with. But i feel too many emotions to know what's the right thing to do. very confused.