It can be difficult, but could you try and trust your friends a bit more? Kinda test the waters with being unavailable to them for some periods of time. Or maybe dedicate a bit more time for your friends? Personal projects can sometimes spiral out of control and you can become obsessed over them, I myself am working on a project as well, and sometimes I work on it unhealthy amounts. Think of what you want and need in life. Is it more time dedicated to work or school or projects? Or would you rather develop relationships and chill with friends? Or something completely different?

I don't know you, and I'm also not a professional in this field (or any field tbh), so I don't mean to come off like I know what is best for you or what you should do. I can only make assumptions based on your post and try to offer some advice. And it is of course up to you what you will do with your life. I would like to ask; do you think you might be sinking in too much time and effort into this project? It is completely valid if it's something you want to do, but you might have to choose between the project and some (hopefully not all!) friends. Maybe you can find the right balance, so that you can keep both. Would it be possible to include your friends in this project? Even just something as small as asking their opinion on something? Or maybe find help from someone else so you wouldn't have to work so much on it yourself.

The situation your friend is in sounds toxic. My parents were always super chill, and now I've been an adult for over a decade, so I've forgotten how the few rules I actually had felt like. I think the only advice to that I have is to just be firm, but understanding with her. Set clear boundaries, but also be there for her when you're able to. You could be a friend that is, maybe a bit distant, but always there if shit really hits the fan.

In the end, do what makes you happy, but remember that social life is also important. We are social creatures, even the most introverted of us. I really wish I would have done things differently and been able to keep some friendships. I'm extremely lonely, even more so now that I had to stop working. I'm stuck in my house, too sick to move somedays, and I don't have a lot of people to talk to. If I lived alone and were to collapse one day, it could take like a week for anyone to really miss me. It's not the worst, there are people who don't have anyone. Just whatever you do in life, don't end up like me.