Don't know wtf to think..

I've been with my SO for about a year. I just found out that for the first 3 months while we were seeing each other that he was meeting with and having sex with several other women. I at this time lived an hr. away, but moved back to this area to be with him. Here is the worst part...is one of these women happen to be my daughters Aunt from a previous relationship! weird right? I'm hurt he lied and said he wasn't talking to other women when he clearly was. I know he has been with many girls before me. and it also bothers me that he has so many girls he was messing with on his fb still and they still reach out to him. I love him, I believe he is being faithful , but still I feel bothered by all this!!!! am i being crazy?? should I just forget about it all???