I plan to sleep with my ex's friend.
Why do you plan to sleep with your ex's friend?
We still keep in touch and talk frequently.
It's understandable that you might have feelings for someone that you spent a lot of time with, but hooking up with a friend of an ex could be problematic. If your ex finds out that you hooked up with their friend, then they will probably think less of you and their friend. It may be better to search for someone that doesn't have any connection to your past relationships.
I'm ok with all the drama and the attention.
Are you even interested in the friend, or are you just starting drama to punish your ex? That's surely not the right thing to do.