As your screen name so aptly points out ... STEP BACK!
YOU can make the offer of having intelligent conversation with your daughter -- and then it is her choice on what to do.
YOUR daughter did the crime (Domestic Violence), and given that she has not made an effort to IMPROVE her behaviors at this time (and has made it worse by moving in with a boyfriend, into drugs and drinking, seems to be a substance abuser) and is in a controlling relationship, the ONLY way she is going to WANT to improve herself, her health, and her status is when ...
THIS ADULT CHILD CHOOSES to do so ...
Because the consequences of NOT changing have forced her to WANT to change at that time.
She OBVIOUSLY does not want to change, either her addictive behaviors, her personal attitudes towards yourself/your spouse, nor does she see anything wrong right now with her selected live-in relationship.
LET her live with the consequences. Be aware that you need to have the phone numbers of shelters available for HER in case she needs help to leave (as well as programs that will take her in to rehab for withdrawal and support newer (and healthier) lifestyles).
SHE made her choices. YOU made yours. RELAX!
PS ... Do you know how much of a THRILL it is to have PEACE, QUIET and RELAXATION in your home ... no Toxic Teens, no Toxic Behaviors .. just the JOY of coming home to YOUR own home that YOUR hard work paid for and KNOWING That you do NOT have to cater to any toxic people anymore! I can tell you from PERSONAL EXPERIENCE ... what JOY! What a THRILL! I am so HAPPY now that it is just GREAT! What a RELIEF to NOT have the stress of Toxic behaviors and problems of a difficult teen in the home .. and that is for SURE! PLUS .. Sitting down is something I can FINALLY do .. because my home is NOW JUST FOR ME ... and my income ... I can FINALLY TREAT MYSELF and enjoy the NEWLY Learned and Discovered Activities that I am learning about .. and that includes newly discovered and HIDDEN TALENTS that I never knew I had all these long, long years of life!
Just went through having both my children leave my household in the past year, and yes, they are not necessarily making good choices at this time. BUT ... yo u need to let the 'birdie' fly from the nest ... and that means taking the CONSEQUENCES of the bad choices with the BENEFITS of healthy, good lifestyles.
YOU have done your best. That is all anyone can ask of you!
For myself -- one adult child willingly helped my ex (from a decade and half ago) to BURGLARIZE my home in August 2006. This is the same ex that BRUTALIZED the children as toddlers, and yes, the same ex that was convicted of child abuse! So yes, I've recognized that they made that 'choice' (which is not good), and I've closed the pocketbook and won't 'enable' poor choices in life. When children turn 18 --we ALL Need to let them GO ... and let them Experience everything that Life as an Adult has .. Consequences, good effects/benefits, whatever. THAT is what being an ADULT means!
So ... take this Empty-Nesting Single Retiree for her word -- RELAX! Have fun ... find a new hobby, start spending your hard-earned income on the one person FORGOTTEN over the past 18+ years -- YOURSELF! You DESERVE to be treated, and pampered and yes, take care of yourself at this time!
But .. keep the communication lines opened. THAT is what is key. She may take YEARS to respond .. but ... sooner or later she will respond .. and ... like myself -- we all will have to bite back on the joyous "I TOLD YOU SO" to keep it from coming out!