<human>: Can you give me the gist of the text in a nutshell?

Over half a year ago, I(19M) was in a long distance relationship with my ex(18F). It lasted almost two years, until she brutally dumped me. Our families got along tremendously, and there were never any problems. And although we still keep in contact (we were good friends before and after the break up), we havent seen each other since the break up. 

Although I still talk to my ex and her family, there are still bitter feelings from me towards my ex. This is because before our two year, I had saved several hundred for a beautiful dinner, necklace, and travel fees to see her (she lives four hours away, but still). During the dinner, she listed of several things she didn't like about me, how she no longer loved me, etc., but she still kept the necklace, made me pay for dinner, the works.

My mom(51F) set up a dinner in a few weeks to meet up with my ex's family. Mainly because my ex lives near my old college, and the fact I put some stuff in a storage unit before transferring to a new college. The unit can only be opened if I am there, so really, I am out of luck. I do not want to go. But I have to. While I love her family, my ex is a whole other story. She tries to drive both families to hate one another simply because we are still friends.

I have mixed feeling about the situation. I have to go either way, and am a little disgruntled that she is. But I am over it all.

I am going either way, and I am going to be the better man. What is the best way to handle all of this while maintaining my composure?
<bot>: My mom set up a dinner with my ex who dumped me horribly and her family without my consent. I am going either way to be the better man. Looking for advice on how to be tactful