Stop putting up with crap just because it was the same crap that you used to do. It wasn't okay when you did it, so it's not okay when someone else does it to you. You don't have some karmic duty to make amends for your past wrongdoings by allowing someone else to abuse or mistreat you.
In fact, you have an olbigation to inform that person that they're wrong (since you now know better). If anything, let their behavior be a mirror of your past transgressions. A reminder of what you used to do.
I've entered into several friendships with people who weren't good friends. They were draining, narcissistic, didn't "get" me, or were just plain incompatible with me. Yet I stayed on course. I did it because I had, at one time or another, been all of those things to someone else. I thought these friendships were my penance. Take a wild guess about how they turned out.
I always ended up feeling drained, depleted and resentful. I harbored those feelings and eventually lose the "friend." It's a silly cycle and it doesn't have to exist.
While I am certain that this pattern is a result of my overly self-critical nature, I also think that this it's rooted in Western culture. We live for punishment and blame. We focus more on where we've gone wrong, and we think that intentionally walking into suffering is our repentance.