I've appreciated the break of a hospital the 2 times I went, once after a sui attempt.
Remeron did help me sleep, even though I didn't find it particularly strong. I hope it works for you.
You need sleep to help you stay stable. Being in the hospital will allow the doctors to medicate you under supervision. To allow you to get sleep, and also work on a med cocktail to keep you stable.

The thought of wanting to harm yourself is scary. I know that at times you may feel totally convinced about your decision, and at other times guilty that you have those thoughts. At the end of the day, you are walking a fine line of staying on control, and not. Don't let that responsibility lie with you if you are so vulnerable-go to hospital.
We'll be here, and maybe you'll have the opportunity to check in here too