Please help me out!

I'm going to try to make this as short as possible! Basically , my boyfriend of a year just told me he was bi . I had no idea ! Actually he didn't tell me, his friend told me. I confronted him and he said its true and I don't know how to feel about it . Knowing in his head he thinks I'm beautiful and he is thinking about other guys as well. What do I do please help me . I need all the opinions in the world right now 
Im going to update you guys and give you more bc you are all saying it doesn't matter : he was cheating on me talking to guys for a while and talking about how he wants to meet up with them and do stuff , we talked about it and he said he wasn't gay or bi and he was just experimenting (While we were dating ) I decided to stay with him because he never actually did anything but talk and now he is telling me he is for a fact 100% bi so I'm a little worried yes. Now what would you guys do . I love him but now I know for a fact he is bi I have a feeling he would cheat on me physically but he swears he would never do that