I think my boyfriend is bi or gay so any advice is helpful

Okay so as the title shows I think my boyfriend could be but unsure. So we've been together now almost a year and half. We live together and he has two kids that live with us and I have three and for the most part out side looking in we are a perfect family (blended) but if you never met us you wouldn't know his weren't mine and mine not his. He's never been married but has three boys by three women which no problem for me. But we are 37 and we had gone to high school graduated together lost touch an in 2009 reconnected and now together. So after we had been together maybe 7 months I was cleaning out his email box that had 6000 messages and he knew I was. Well I came across and email that just caught my attention. Well it was to a guy and my bf stating how he wanted something from that guy and wanted it bad. Well if you could imagine my utter shock. I sat there in a daze well so as I went on I found more and more and on craigslist I found ad's posted. Now all of this was before me expect for one incident. From what I could tell this lifestyle for him had gone on for almost 2 years. I had no clue how to confront him not sure what to expect. So I sat and waited and curiousity got the best of me and I was able to contact this one particular partner that from the way it looked they had spent the most time together. Well just my luck this one person has now become my worst nightmare but in the beginning he was so forth coming I was upfront with who I was and that my bf didn't know that I knew anything. Well somehow I got caught by bf he saw an email and didn't realize whom I was talking to and assumed the worst that I was cheating.. So long story short he leaves me out side locked out of our house calls me every name you can think of and leaves. So I sent him a text and said well I didn't want to confront you this way but that is from your past not me cheating. I popped off some lines from old emails from them and mention this person name and said now what do you have to say. All I got at that point was its my past and I'm ashamed of it and it was all drug induced nothing more to say. And refused to talk anymore about it. Well come to find out that only one day after we had decided we would be exclusive with one another after dating a few weeks he was texting this person I guess call him Joe and asked Joe for sex. when Joe denied him he continued for two weeks constantly being denied. So for me He didn't actually have sex with someone else but he in my mind cheated because he actively pursued another person for sex regardless if they were male. From my knowledge to today he hasn't done that again with that person. Now Joe is very much in love with my bf. He claimed that just two weeks before my first date with my now bf that my bf had spent time with him and when they had sex it wasn't drug induced that time that he thought they were going to start a real relationship he was to meet my bf family kids all of it. Then my now bf left and two weeks later we went out and he blew Joe off until after we were bf/gf. All I can get out of him is that it's his past leave it alone. That he's not that person anymore and only wants me and no one else and has no thoughts about the past never thinks about being with any man nothing. So I guess is that truly possible. Are am I just wishful thinking he's telling me his honest thoughts and wants and desires? Also Joe will not go away he drives by our house he text me constantly giving me information that I don't want has sent me a video of them when they were together had done his best to run me off. So I'm at a lost of what to do,

 

I'm fine with past is past. I've never been one to judge anyone regardless of what preference they have sexual. Just to me some things don't add up. But if I'm to tell all my past secrets then so should he regardless of shame or what ever it is he did. Things for us have changed to a complete 360. He isn't the same bf to me any more. I don't view him differently at all but he treats me so different.