Am I the reason my daughter has bpd?

[mamalynn]

I may have used this forum before several years ago, I'm not sure, but feel in the need of encouragement. My 30 y.o. adult daughter is currently receiving therapy for bpd. We (her parents) are paying her copays for therapy and medical needs as she is not currently working. She is being supported by her boyfriend for most living costs (we pay car insurance and for her phone). She lives in another state. When she is splitting, particularly if I have said something to upset her, she verbally attacks me (usually by text) saying I am the reason she is the way she is and why she has bpd. She also cusses me out, and says other cruel things about me. I usually do not respond, and if it gets too bad, will block her for a few days. I have a hard time accepting that I am the cause of her bpd. We adopted her as a baby, and she does have attachment issues, but we had a fairly normal, loving family life, stable marriage, no alcohol or drug abuse, no physical, sexual or emotional abuse. She has 2 brothers, 3 and 5 years older than she is, who basically got along with typical sibling squabbles. As far as we are aware, there were no major traumas. I was by no means perfect, but read a lot of parenting books, sought therapy for her and myself as issues developed, and honestly do not believe my husband or I mistreated her in any way. Yet it seems I am the root of all her problems.
My husband is 81 and has kidney cancer, and is awaiting surgery. Before he was diagnosed, my daughter announced her engagement and wants to come home for the wedding. We have offered to pay for the wedding with a small budget, and I have tried very hard to help by sending information on venues and caterers she expressed interest in, giving her several options from which to pick, and putting deposits down. Now she is saying that I am doing everything my way (I truly am not!) She and her boyfriend would break up every two or three weeks, and she would call and tell me the wedding was off (so he could hear her telling me), and he would tell her he was leaving, and then a few days later everything would be okay. I set a boundary saying they could call and vent if they were arguing, but I did not want to keep hearing about the wedding being called off if they wanted me to put money down for deposits. They did pretty well for awhile, but recently did it again. I ignored it, and let things settle, then reminded her that I didn't want to hear it which is why she is currently angry with me accusing me of threatening her (I just don't want to keep spending money on a wedding that may or may not take place.) Now she's saying I'm the one who wanted the wedding and I'm making all the choices - ??? what? I don't even like her choice of caterer, but never even expressed an opinion on it, just kept saying it was up to her, and the one she chose was fine! Now I don't know if the wedding is on or off, if she wants it or not, or if I just need to bow out of it altogether. So far, if I cut my losses it will only be about $3000. Do I just wait until she is over her current hatred of me, and wait until she starts reaching out again acting as if none of the past week and the horrible things she has said happened? I am not inclined to just give her the rest of the money I had budgeted because if the wedding does go on, the vendors will need to be paid the balance of what is owed, and there are still major details and things that need to be paid for. And she has no idea what things cost, and we are not rich people. I truly have not been the one making the choices, and I don't know why she says I have. At this point, I'm just sick to death of the whole thing, and with needing to take care of my husband, don't have the energy to deal with her bpd.
Any suggestions?

Our objective is to better understand the struggles our child faces and to learn the skills to improve our relationship and provide a supportive environment and also improve on our own emotional responses, attitudes and effectiveness as a family leaders