It sounds like she may be stuck in a pretty crappy relationship. You can't force her to leave, but you can offer to listen should she ever needs it and maybe have some info handy on where she can go to get help should she ever ask. What I might suggest is this, though you know you and your friend better than I, I am a huge believer in just being honest and up front.
"Hey lady, I wanted to invite you to my party etc. Because you are my friend and I love yeah, I really want you to come. But also because you are my friend, I am gonna be honest. There is no judgment here, but I worry about you and your relationship with your boyfriend. The way he treats you makes me worry and I just want you to know if you ever need to talk I am here. I understand that you love him, but he has shown some behavior towards you, myself and my friends in the past that I struggle with. So that being said, I would rather not have him at the party. It would mean the world to me if you could attend, but I also understand this may put you/us in an awkward position and so whatever you decide I am okay with and still here for you."
Sappy but I feel like it would express the message that you want to stay friends, you love her but that her boyfriend is not welcome under your roof. Shoot someone that messed up wouldn't be allowed near my door! :) Best of luck!