Moving out at 17

I’m 17 currently spending the entire summer in New York with my boyfriend and his family. I live in PA with my family and my boyfriend, but we came down for the summer to visit his family and stay with them. His family is honestly so great and they helped me with so much including getting a summer job which is why my mom is letting me stay in NY for the summer. She also told me today that she wants me to stay here for the summer because life back in PA isn’t so great. We’re about to lose our house, my mom is really depressed and started to drink frequently. My sisters bf is being investigated for beating her kids, there is just a lot of drama that goes on in my family and I can’t handle being around it anymore. Back home I’m so depressed and unmotivated, but in New York I’m so happy and exicted to be working and I’m just overall less depressed. Yes, I still have days were i feel very down and anxious, but for the most part I love where I am right now. My question is how do I go about telling my mom that I want to stay here for good? obviously I need her consent to live in ny, but I don’t want to be harsh and ruin my relationship with her. Shes beginning to be understanding ever since my dad died in 2015 so I’m hoping she’ll be understanding about this, but I’m not sure. Any opinions and advice is appreciated!