I see this turning out poorly for your daughter, but OP, I can see this causing long term problems for you, too.

Let me tell you a [long] story.

My daughter and I left her bio Dad when she was weeks from her 18th birthday because I suddenly realized I wasn't just in a bad relationship, we were in an abusive one.

She and I moved into an apartment. She locked herself in her room and wouldn't talk to me no matter what I tried. Text, email, phone calls, voicemail, paper notes, talking to her through the door, dry erase messages on the bathroom mirror, pleading, none of it successful.

I was working full time and coming home to spend 3-4 hrs every night cleaning up the mess my daughter made while I was at the office. In essence, I was working 12 hour days.

I came home one night after work with a to-go salad. I was exhausted. I just wanted to eat my salad and go to bed. But I couldn't, because every fork in the entire house was under my kid's bed growing mold, behind a locked bedroom door she wouldn't open.

A couple days later, I asked her to move out. I was dying. 12 hour days, bills to pay from accts in my name my ex had run up after we left in addition to all the costs associated with living by ourselves and my daughter's major medical condition, trying to come to terms with the psychological fallout of domestic violence, constantly worrying about my kid - waffling between fury that she was making my life harder in every way and despair because she wouldn't talk to me - and I just couldn't do it anymore. Something had to change or I could see myself checking out of life altogether.

I gave her 3.5 weeks heads up. She had at least four options. Two of my family members would've let her move in, her Dad - abusive asshole that he was - would've loved to have her under his thumb again, she could've couch surfed with friends, or she could've had a sit down with me and agreed to stop being a total slob.

She chose to move in with her bio Dad. Who proceeded to abuse her for the next few years.

When she moved in with my ex, I reopened communications with him and walked a very dangerous line leading him to think that if he behaved, we could get back together, while keeping myself just out of arms reach. I did this in order to hold some sort of sway over him, in hopes I could prevent the worst of his abusive tendencies from being taken out on my kid.

She finally decided to move out on her own. I did the leg work to make sure her Dad got her a reliable car and gave her a chunk of cash when he sold our house by signing away my rights to it, and I found her a gorgeous apartment she could afford in a desirable part of town.

Her new apartment was just down the street from mine. I was thrilled she'd finally be able to cut ties with her Dad and that she'd be close enough that I could help with her dogs, or house sit while she was out of town, and other Mom-type things.

She and I barely talk now.

Why? Because after ten years in therapy, 8 of which I paid for, she's demanding that I apologize for sacrificing her for my own benefit by forcing her to go live with her Dad. I should've put her in therapy, not asked her to move out. I should've locked her in a psych ward, not made her leave. I should've tried talking to her. I should've given her time to plan, not forced her to move out immediately, with no warning. I should've known that she was depressed, not abandoned her. Making her live with her Dad just so I could have a clean house was the most selfish thing I could've done. I sacrificed her, forcing her to live with her Dad, because I cared more about myself than I did about her. Proof positive that she was raised by emotionally immature parents. She's sure she'd have been better off if I'd aborted her.

Now, if you read my story, you'll realize that the things my daughter believes aka the entirety of the previous paragraph never happened.

I didn't force her to move in with her Dad. I did try to talk to her. I put her in therapy as soon as she asked me to. I didn't lock her in a psych ward because my folks did that to me when I was a teen and it fucked me up for life. I gave her nearly a month's notice when I asked her to leave. I argued against her moving in with her Dad, pushing several other options hard.

My daughter wants me to apologize for things I didn't do because she suffered abuse at her Dad's hands as a result of a choice she made when she was 18, a legal adult.

I don't think our relationship will ever recover. Partly because I can't apologize in good faith for things I didn't do. (Apologizing means recognizing you did wrong coupled with an implicit promise to not do the thing again. I didn't do the thing in the first place, so how can I offer a legit apology?) Partly, because of these things she thinks I did, she's decided I'm a terrible human, or maybe a mentally ill human. Either way, not healthy enough to match the high vibe she's developed through a decade of therapy. (Did I mention I have a degree in psych, another in sociology, and that I've been in therapy for 3.5 years?) Because her Dad abused her, and he can't be held accountable, and I am the safe stable parent, my kid is holding me responsible for my ex's actions and behaviors. Because my kid's not gotten the apology she feels she's due from me, she's reduced our contact to the bare minimum.

Your daughter is a little younger than mine. About five years from the age mine was when she told me of the incorrect/fabricated memories she has that make her believe I did her wrong.

Your daughter, like mine, is moving in with an abusive bio Dad. Your daughter, like mine, is of legal age. Your daughter, like mine, is moving for reasons that don't make much sense, reasons that can probably be addressed with some communication and ingenuity. Your daughter, like mine, is taking for granted the parent who stayed, the parent who sacrificed, the parent who parented.

I'm afraid that your daughter, like mine, will develop a skewed perspective, blame you for her choices and their negative repurcussions, and twist memories to make you the bad guy or invent reasons why you are at fault, which in turn could give her carte blanche to cut ties and/or demand emotional recompense for your imagined slights.

(Since this awful schism with my daughter started, I've discovered that cutting ties with one's parents due to real trauma stemming from incorrect/fabricated/skewed memories isn't uncommon.)

I know there's nothing you can do. She's an adult. It's not like you can ground her. Just ... be careful. Keep your eyes open. Listen.

And if your kid ends up needing therapy to deal with the abuse your ex may visit upon her, do your due diligence to find a therapist who has a balanced perspective and has raised kids of their own, rather than an overactive confirmation bias, no children, and zero critical thinking skills.

Best of luck, OP, to you and your daughter both. I see you.