Is it ok for my ex fiance to ask me to pay for her bills on top of providing for my kids with a boyfriend that works and stays with her parents?

My ex fiance cheated on me and left me while I was in jail after promising she would be there. I found out through a screenshot from my family, not from her. We had a lot of issues together but work better as co parents and and friends. Any time she asks I send food for the kids and get them what they need. Her boyfriend lives with her, the kids and her parents. Recently she has asked for 1200$ to help her parents pay the mortgage on their house I didn't send it because I couldn't do it. I had to send food twice in the last week for the kids and just today she messages me asking if I could send $200 so they could go to Sam's club and buy toilet paper paper towels and meet for the house. I'm trying to figure out why this is okay in her mind when she has a boyfriend but still asking me to help with house stuff outside of taking care of my kids when we are no longer together.

Is it ok for my ex fiance to ask me to pay for her bills on top of providing for my kids with a boyfriend that works and stays with her parents?
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