Dilemma

So a few months ago my grandmother remortgaged her house because my mother told her that she wanted to pay off both me and my mothers car off that were in my grandmothers name as a co signer. She agreed only if I give my mother the $200 a month to pay the mortgage while she only paid $75 a month. Both cars cost the same(20,000 each) plus my mom has money left over to pay off her own personal debt. I just paid off $13,000 on the car & the rest on bills I had so I could move out and find An apartment. My grandmother said it was fine to get out the mortgage since she's leaving my mother the house anyways in a few years. This is the dilemma. My mother told me to not worry and to NOT PAT the $200 because she wants me to look for a good place to live and where I'm from, apartments are expensive. I TOLD HER ARE YOU SURE? I don't mind paying back at all! I told her if she was ok? She said yes. So I found a 1 BR for $1700 a month. Not including utilities. I only make $4000 a month myself. My mother said it was fine and not to pay but I felt bad since with moving out and saving I wouldn't help. Well not every month she yells at me or asked me for the $200. I told when why did she say it was ok for me to get an expensive apartment if she wanted me to pay if I moved out? I would of been ok only paying $1300 for rent and paying her back no problem. Now she's saying my grandmother is mad for me getting money and that she should of given it all to my mother to help her get out of debt & my mom keeps boasting about if it wasn't for her that my grandmother wouldn't of agreed and in the reason that I have good credit and could get an apartment. It's annoying me a little and kind of pissing me because it makes me feel bad that I can't help like i want to. My mother still keeps asking me for money knowing I can barely afford it to move out & she's mad I got half of the money from remortgaging my grandmothers house and bragging is was because of her when it's not even officially her house.. she's going to sale it once my grandmother gives it to her. Idk should I feel bad for even taking that offer? Am I bad for not helping when tho I can't ? Is my mother being kind of unreasonable? Idk....

I'm already thinking To just pay the $200 no matter my living situation.