While her friend is here...
So take a back seat and wait it out.
I don't know what answers you are looking for when you say she got back together for the wrong reasons only to go on to justifying being back with her by saying she is in love with you.
She sees that she can say and do whatever she wants and you will simply go along with it so she is going to continue to pull your puppet strings and see how far she can push it.
If that is what you call love go right ahead.