I need some advice.

I've been with my current boyfriend for about 3 months now and it's pretty great compared to my last relationships. I've had a lot of bad manipulation in my relationships and this one is the first one that hasn't been like that. But because of that, I don't trust him 100%. Any time he's on his phone I think he's talking to other guys and it makes me feel so horrible. Now I've found a video of him giving a blowjob to another guy who is, how shall I say, larger than me. I'm not sure if this is a video from before we met, but that's what id like to think because I really love him. Its now hard for me to look at him and I'm not sure what to do or what to think. Is this all in my head and am I just being too controlled by my emotions?