My boyfriend cheated on me with my best friend and I'm really upset and mad at both of them. Advice please?

I'm so sorry! First of all, don't let him off the hook very easily. If you are mad, be mad! Make sure they both know how much they hurt you, and what an awful thing it was that they did. If you are really best friends with this girl, then eventually you two will be able to make up. But guys who cheat aren't usually worth it. Sisters over misters always, but she still has to know how much she hurt you. I guess time heals all, so just wait them out a little while to see how you feel maybe? Good luck<3