If I could, I would say something really supportive. but I just dont see where I have any where to go with your post. I can say I understand what it's like to cut and be cut by alters, and have alters abuse people you care about. As well as what it's like watch helplessly from inside as an alter wreaks havok, and as one methodicaly prepares to commit suicide. somthing happened and got control back at the last second.
it's the reason I hang on so tight. but this isn't aobut me.
amandalouise covered all the bases as far as getting in contact with your therapist, or Dr. or whatever kind of psyc. help you have. I you haven't, you need to. they need to know. And said the one thing I can say for sure, already.
the first thing you have to work on is stability. and you need to get some communication inside. Your alts need to know it's not okay to behave this way, and that they are hurting everyone. Not just you. not just your BF.
that made a difference for one of my "problem" alts. when they found out they were hurting and scaring young ones, it upset them.
If I have learned one thing, it's that alters are not just single sided. there's more to them than just the attitude you see most often. there are reasons for why they behave the wat they do. but they don't always understand "the big picture", they don't know allways know everything you know(and vise versa), or that what they do effects all of you.
if your not in therapy, you need to be. and if you are you need to tell your T everything that's happening. And you need to get some communication happening inside. alters aren't inhuman monsters. they aren't machines built to destroy. they have feelings, wants,and needs, and quite often in my case they have been scared and confused children.
but just being scared and confused is enough.
I hope you working things out. I have heard that hospital stays can be an opportunity to focus on getting things straightened out, without having everyday life distracting you. that it can be a real turning point. I can't say that from experience, but it's what I've heard.
It's something to consider.
I wish you the best.

jax