Bad mother/reacting in anger

I have a question about how to deal with my overwhelming anger when it arises. My daughter came home at the end of October on stress leave from university. She is suffering severe PTSD from a sexual assault, anxiety and depression. She was suicidal the first 2 months after returning, to the extent of having to call ambulances and spending time in Emerg.

My daughter and I have had a fraught relationship for a few years and she has a lot of anger towards me as a result of my decision to leave her father and my later decision to marry a man who ended up being verbally and emotionally abusive to both my daughter and me (ultimately leading me to leave him as well). I have a lot of guilt about the impact of these decisions on my daughter and the impact on her home life.

My daughter chose to live mostly with her father during my brief second marriage. I continued to see her regularly for meals and to drive her to school, take her to appointments etc., hire tutors etc. When we did spend time together, she was often angry and yelled and cussed at me a lot. I used to get defensive and we would have huge arguments. Over time, I learned to just give her time and space to vent. I supported her financially and logistically, helped her with her moves to and from university, etc. But sometimes the yelling and accusations and cussing would get to me. So we would go through a pattern. I would deal calmly with her for weeks. But then, usually when I’m feeling low and felt she was being vicious or unfair, I would yell back.

After her return from university in October, she decided to stay with me and we have mostly had a calmer relationship. One decision she made was to get a puppy to train as a service dog for anxiety and safety. I supported this decision and bought the dog for her in January. The puppy has been both helpful (animals bring our my daughter’s soft side) and stressful (hard to train, barking, peeing everywhere – as puppies do). My daughter wants to do all the dog training, but often leaves her dog alone with me unannounced, and she does not consistently follow through with the training program. We hired a trainer who said we all needed to be in on the training. I help where I can, including sitting with the dog when my daughter is often out. Last night, my daughter left for the evening, said she’s be back “soon”, but fell asleep at her boyfriend’s place. I called her in the middle of the night and she said she would come back in the morning. When I got up this morning, she was not back yet. As I had a dentist appointment, I took her dog out of the crate and for a walk beforehand. When I returned from the walk, my daughter was home, waiting for me, and when I walked in the door, she flew into a rage accusing me of thwarting the dog’s training and messing everything up for her. She accused me of treating her like an incompetent child. My daughter was swearing and yelling at me, calling me names etc. I’m afraid I lost it, and our conversation degenerated into a “F you” back and forth.
Worse, I made some caustic observations about her lack of attention to the training, with the result that the puppy is not even house trained yet after 7 weeks. When I returned, she has taken the dog to a friend’s and won’t answer my texts.

So now I am feeling like a terrible mother. It feels like no matter how hard I try to be patient and calm and do everything I can for my daughter to support her and care for her and pay for her treatments and hold space to listen to her, we eventually have a fight like this one. After these fights, I apologize, she does not, and she usually punishes me for awhile. I have done so many models on my relationship with her and these help often. But then we get to a point where she attacks me (I know that is a thought, but the C is daughter yelling “Fuck you. You’re thwarting everything I do! What the fuck are you taking my dog out for a walk!!! You’re a fucking bitch!!!”) when I thought I was doing something helpful. Then, instead of remaining calm and finding compassion for her, I fell defensive, flooded with anger and attack her back.

Afterwards, I feel so terrible and live in self recrimination. Who behaves like this with a daughter who is known to be suicidal? I experience so much suffering about this. I keep thinking that I have it together, that I won’t react in anger, but then it happens again. Do you have any coaching insights to help me deal better with the flood of anger at the time? Or how to forgive myself afterwards when I do lose it? None of the thoughts or laddering thoughts I am able to come up with seem believable or reduce my suffering.