I realize that the daughter is 17, and will be out soon. But there are times when a child doesn't get to get out at 18. Is the new bf wanting to raise a child for a year? Would leaving her with her dad be an option if he has threatened violence? Is any of this really a good thing for her to be seeing? I know marriages break up, and when there are children involved still living in the house and a minor there are other things to think of.
Knowing your marriage is over, and wanting the freedom to go on with boyfriend,you and your daughter having an apartment and getting her thru the next year, might be an option. Then you have the freedom to do anything you wish. The boyfriend would certainly understand (or should) that you could date until the daughter was out, then move in together if you and him are still in a relationship.