I think my dad is having an affair with my best friend. Please help?

I've never had an experience like this, maybe sitting Angela down and talking to her about it. Ask her questions about the trip and the progress of the report. Don't be afraid to ask your dad, just say how your feeling and that it hurts you. Let Angela and your dad know that you think something is going on between your friend and your dad. Its your right to know. Talk to your mom and tell her how you feel if she feels the same way, both of you can sit and confront your dad so you don't have to do it alone. I don't know if this helps. Im sorry and i hope everything turns out ok!