Think my best friend is trying to have with my ex?

Ok, so my ex broke up with me about a week ago, and my friend just recetly broke it off with his girlfriend. Ive been hanging out with my friend for a few days now and he keeps bringing up my ex. He said "would you be mad if i had with her" and "would you be mad if i got her to send me naked pictures" and i responded with a yes to both of them. Then he SWORE to me that he would never do anythign with her. Then yesterday, he says that i should hook up with one of his exs from about 3 months ago and says "dude, you should date kaitlyn, i promise, i wont be mad". That right there just kinda seems like he is looking for my approval so that he could have with my ex without hurting my feelings. Then last night he tells me that his dad(his dad left him and his mom when he was a baby) has recently made contact with him and that he is going to visit him tomorrow. Then i asked where he lived and he said that his dad lived in Canton....the same town where my ex lives. I wnat to know what you all think he is up to. I think that hes trying to do somthing behind my back. But i can fell it.....my gut is telling me that he is up to something. Opinions please. And if I find out that he does screw her, how should i react to that? Should i be mad? What would you do