You're not worthless to me, or the other posters on this thread, and you're certainly not worthless to your beautiful daughter. We all have down moments when we feel we're not good enough for our children, I certainly did, (mine are adults, and parents themselves now) and I'm long-married to a decent bloke, not in a relationship with a fuckwit who puts me down at every opportunity.
You can learn from your horrible experiences, and pass your knowledge on to your daughter as she grows. I don't mean tell her the gory details, she doesn't need that, but you can teach her not to take shit from anyone, and you can teach her by example.
I can't remember if anyone has suggested the Freedom Programme from Women's Aid to you yet, but it's worth a google. Also, there's a book called "Why does he do that?" by an author called Lundy Bancroft, which will shed some light.
We're not supposed to do hugs in this nest of vipers, but I send you some anyway.