Me and my ex broke up 2 months ago but we have been off and on for like 2 years. Now he is trying to get with my best friend and it hurts. I feel like I can trust her to not date him but I don't know. I miss him a lot. What should I do?

You can't trust her and she is your best friend?
That makes me wonder about your friendship with her.
Unfortunately you cannot stop if they are going to date.
But you can do things for yourself. Go get your hair done, go out with other friends, go running if that makes you feel good.

Get a new best friend, a real one, and move on with your life and don't be pining for someone who has been gone for 2 months.

If you believe your friend is actively flirting back with your exboyfriend you should confront her and ask her what's going on (that is, if she really is your best friend). If she is interested you should let her know how you feel and that it makes you not trust her. If she continues to flirt with him, I would suggest stop talking to the both.

Well I have confronted her about all this and she says that she only likes him as a friend but yet she rubs everything in my face about how he flirts with her. The reason I can't trust anybody is because I have already had one friend to stab me in the back with this before.

You should talk to your friend who he plans on asking out and tell her how you feel about his plan and tell her how much it hurts,the way u still feel about him, and then tell her that you trust her not to hurt your feelings.

Lovesit, honey, do you know the saying "stick with the winners?" How about hanging with some different people, like people who know the meaning of honor. Unless, of course, there is something in it for you in attracting uncaring, superficial, selfish people for boyfriends and best girlfriends, ex or otherwise. Sometimes, as we grow up, we get caught up in drama instread of creating a life for ourselves. Reconsider who you are calling friend. Reconsider who you are letting have your time and attention. Maybe a little more attention needs to be paid to your life. Learn how to drop friends that aren't friends now, it will be a handy skill to have all your life.