How do I tell my mom I just want to see her every other weekend?

My parents got divorced 5 years ago and they are now both remarried. My Mom is good, but she’s not very responsible or stable. Her, her husband, and my baby brother live with my grandma still. My Mom never has money to pay her bills and her phone always gets turned off. Last year I decided to live with my Dad and stepmom and I don’t want to go back to my Mom’s. The arrangement is that I am with my Mom weekends, breaks, and summer vacation. But, I’d rather just live with my Dad and stepmom and see my Mom every other weekend. I have a lot of activities here with my Dad and I have my own life. How do I tell my Mom that I’d rather be with my Dad permanently and only visit every other weekend. Everytime I try and talk to her, she always gets angry or offended, starts yelling at me or gives me a huge guilt trip. It’s kind of immature that she does that, but I don’t want to hurt her feelings either. I don’t know what to do, I can never rely on her for anything they way I can with my Dad and stepmom. My stepmom has given all of her time to taking care of me and my Dad. It’s the perfect stable family, and I love it. Okay, not perfect, but almost perfect!