Jd,
Once again, you are supposed to protect her in someway like the big white elephant in the room? I am sure it was no surprise to the friend either.
During the last few years of my marriage and after the divorce I told people my axh was an addict. I lived in secrecy for 30 plus years and it nearly ate me alive. I would not do it again.
You are being honest and I feel you have done nothing wrong. I am sorry that your aw doesn't want to take ownership of her what she has done. I am sure it was uncomfortable for you to even tell this friend your personal truth. Hang in there, you owe her nothing.