My ex hasn't seen my daughter since april........?

You are too soft. Don't engage in this. There is a time to comfort and make her feel better, and a time to be more matter of fact. This is the latter. "Sorry sweetie, you have to go see your daddy, I promise it will be fun". And that's that. She is 2, she's gonna cry. She probably gets hysterical when she can't find her shoes or spills her juice, too.