Recently had the same exact problem with my ex.
Except sometimes she would try purposely pissing me off saying how hot other guys were and stuff but then the same night she would tell me she still loves me and stuff (tf right?)
So I then got this urge to piss her off sometimes for fun but it wasn't worth it and it was very stupid/immature. So I just stopped messaging her/contact with her in person.

She tries messaging me but I pretty much have her on ignore on everything (Facebook, instagram, Kik, skype, viber, etc.) Anything.

Now, I know you don't want to end the friendship but have you told her that you still have feelings for her and it makes you uncomfortable when she mentions her boyfriend to you?
If not then try it. If she says a smart ass comment back to you or threatens "then leave!" Then do it. She'll realize it sooner or later. Try asking if she wants to hangout in person some day and try keeping her boyfriend out of it.

Now, what YOU can do is talk to another girl. What I mean by this is actually try talking to a girl that attracts you. Don't force yourself to like someone because that's just donkey **** coming out of your ass. When you talk to another girl and you both like each other then you're pretty much focused on THAT girl and nothing else. You won't think about your ex or anything else that bothers you. Just that girl.