My best friend is getting really close of my ex and that's upsetting me.
Do you have someone you can talk to?
No, I am always busy.
There was a reason you broke up with them so you should not be jealous about it. It might help to make some new friends who you can talk to about it.
I don't want to make new friends, they are annoying.
If this is really hurting you that much you should talk to your friend about it. A lot of people deal of jealousy, but it may be more beneficial just the occupy your mind with something else.