How would I be able to make this homie hopping ok?

I went out with this guy for about 3 and a half months and he was In la la love with me. I broke up with him and I went out with another guy for about a month like 10 days after we broke up. So I have always had a major crush on my 3 months Exs best friend and now we might go out. How would I make this ok with My 3 month Ex even though we are still really good friends.?