How to get ex to stop bothering me?

I have a daughter with my ex and we share joint legal custody and joint physicla custody however she lives with her mom a majority of the time. I am ordered to pay support and i do. I have a daughter who lives with me that i have custody of by another woman. My ex constantly is asking me for money and if I dont give it to her she makes me feel bad. I cant afford to do it all the time. When I dont she says Im treating my daughter bad. I dont feel thats true at all. I pay my support adn Im there for my daughter but I have bills to. She constantly is degrading me and I cant take anymore. What do you think I should do