My H would say that I deserve someone who wont hurt me like he did too. I hate it when he says that junk. I tried telling him that that was my decision to make, but that didnt seem to do much, so I finally said, you did hurt me, bad, but you are going to have to forgive yourself sometime. That seemed to make more of an impact, we actually started to talk about forgiveness and we didnt broach the topic of reconciliation that time. But, I think that stopping arguing with him about the stinking "You deserve someone who wont hurt you so bad" line was way more effective.
I think that they are ashamed of what they have done, and human beings really, really dont like to feel shame. Its easier to just be sad that your ending your M than for them to face (and deal with) their shame.
The birthday party sounds like a great chance to show off your shiny new self! Dont be reactive, and remember to have a great time! Good luck!
I guess I gave the wrong finger to the wrong man...