I feel you. Sometimes I feel like being suicidal is like a worm in my brain. It got in a long time ago and it's always there no matter what is going on in my life.
I've recently stopped feeling guilty though, and stopped acting. I don't go around going "I'm gonna kms" all the time, but I have allowed certain people to know I'm suicidal, and allowed myself to live how I want and not put on a mask. This has been interesting. I feel like I made friends with my suicide. I have it planned out almost to my satisfaction, and I know I will be able to go through with it at the time I decide it's time. Paradoxically, that's taken away a lot of the panicky feeling I used to have like I was trapped and have to ctb NOW. I know my death is my personal thing and I am allowed to have my own relationship to it, I'm allowed to choose how and when to go. I'm allowed to feel positively about it. Other people are allowed to be very sad and upset about my death, but those are their own feelings. I don't need to take on their feelings about it. I don't need to feel guilty.
It sounds like I have about a decade on you in age, and it took me a long time to get to this point. When I was in college I felt very much like you and ruined my relationship with my gf and pushed other people away. My advice is to try and get some therapy. Not to "fix" you but to try to get a more understanding relationship with yourself. You have a lot of questions like "why do I feel this way, what's wrong with me, how can I do this to the people who care about me" and a lot of feelings like you are faking or acting, like your real self and real feelings are too much for other people and have to be hidden.
I think the most important thing in this life is to be able to feel authentic and like you are being the real you. For some of us that real us includes being suicidal. Therapy really helped me to understand myself and accept myself. It didn't take away the depressed and suicidal parts of me, it didn't "fix" me, and I still suffer. But it helped me be me without shame. And I think we all need and deserve that.
Especially if you had a toxic family you probably have some trauma and fucked up identity issues... Therapy can definitely help you heal from the effects of growing up in that way.
Yeah having constant crises and attempts is really horrible to put on people around you. But being able to talk and share how you're feeling is not bad, and you might be surprised how resilient people can be and how capable they are of hearing hard things. Maybe there's one person you feel like you can open up to a little, a friend maybe?
Sorry things are so hard right now. I think also going through a big change like starting school and moving from a shitty family environment can be a lot to handle. Try to be patient and give yourself time to figure things out