Here's a twist:
What if the toxic person was an established member of the group? Say, if YOU were the new person, and the wife/established partner was the toxic one? THEN what do you do? You, having less seniority, how do you kick that member out? Should you? How would you even begin to go about that?
My point is, if you and he are established....and she is earning her way in, then, seriously, tell him that she goes. Or say all three of you need to talk things out. Whatever it is that you need to do to make your home secure. It's your right.
Once she's an established member, and has equal rights to you, you're not going to be able to do anything about it.
...also, don't get held up over apologies. They probably won't happen. Your husband should provide you support for this.