Why do I still do this??

So I haven't been with my daughters father in 4 years. I can't stand him and never ever want to be with him again! So why in the hell do I dress up when I know I'm going to see him.  I literally go to pick out my clothes and instinctively grab something I know I look good in. Why do I do this, I left him because he didn't know how to be a father and still doesn't.  I despise him for his lack of responsibility. I'm in an amazing relationship and love my fiancé he's a great dad to my little girl and I couldn't see myself with anyone else. So why do I think I need to look good when I see my ex?  Do I want him to be jealous? Is it because I want him to know Ive got it together and I'ma good Mom, that can raise my daughter without him. Ugh does anyone else do this?