Birth father and birthday parties

It's my birth daughter's birthday in a few weeks, and I'm very excited for her birthday party. Her birth father attended last year, and is invited again this year. Aside from some twinges of resentment (he didn't do a thing to help with her while I was pregnant and I ended up needing a restraining order for a time) I hope he comes. I know it's good for her to have a good relationship with her birth father, and I want him to be there for her. Even though I hate to admit it, I treasure the one photo I have of the three of us together at that party. I know I'm going to have a lot of mixed feelings after I see him. I have no doubt that I can be civil to him, but I also know that I am going to feel both bitterness toward him and longing for what might have been after I see him. I feel great peace and have come to terms with my adoption, but it's pretty likely that seeing him will stir up the grief again. I have him blocked on my phone and social media, which is best for everyone. Any tips on how to work through this beforehand?