PLEASE I NEED HELP. My mom stole from my dad and I don't know what to do?

Anonymous
my parents are not together and do not get along. They fight over lots of things and I'm usually in the middle, torn over who's side to be on. So anyways my mom doesn't make a lot of money and is always looking for opportunities to get some, (I don't think she's a thief though..) My dad paid $70 for me to be on a softball team, which ended up being a total mess and the coaching sucked which pissed my mom off. My dad was mad about it too but never considered a refund. My mom however took it upon herself to demand a refund and they sent the money that my dad paid back to her. My dad has no clue this happened and I only know because my mom told me she got the money back and she gave me the option to 1. Dad doesn't have to know, we can put this money towards band camp. Or 2. We can explain why we got a refund and give him his check back. I told her I would not keep it a secret from my dad and that we need to give the money back. So a few weeks have passed and my mom didn't bring up the check, probably hoping I'd forget about it. But I didn't forget because I could tell from the start that she was trying to be sneaky about keeping the money for herself. I asked her today if she had the check for dad still and she thought for a second, said no, that she CASHED it (not ok with me) "but she has the cash." I know she's not planning on giving it back to him, unless I get into an argument with her about it and I can't. That would tear apart our relationship for reasons hard to explain. I love my mom but she did the wrong thing and I can't just let it slip. I'm afraid to tell my dad because he would be furious and my family would go through some extreme situations especially if this was taken to court. I don't want to participate in that but I don't want to help my mom get away with it. I also don't want my mom to hate me for choosing my dad and believe me, she will. I'm the only one who knows she took his money. if anyone else confronted her about it all fingers point to me.
Updates
+1 y
Im not sure if I made this clear, but my parents are divorced. They aren't together.
PLEASE I NEED HELP. My mom stole from my dad and I don't know what to do?
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