AITA for being mean and hostile my first (only) time at a support group?

My five year old started kindergarten last year, and his teacher recommended he get screened for a learning disability. The specialist diagnosed him with ASD, and now he has a 504 plan. The specialist also recommended a support group for mothers (but not fathers, which I found weird) and said it would be really helpful for me because I'd be able to benefit from the experience of other moms. He gave me the information for a local group he said he knew several members of.

I did go yesterday. I left my son with my husband because I wasn't sure what to expect. I showed up and saw a few mothers and children. Right away I noticed that several were not engaged with their children at all and had them sat in a corner with tablets. They were very welcoming to me at first and invited me to sit with them.

I intended to keep quiet and listen, because it was my first time. The other mothers were eager to talk to me and "explain the roadmap" to me. They said some things that shocked me, including several hurtful things about their children that were in earshot. One mother said "there will be days you absolutely hate your child" and then looked over at her son! They also said "be prepared for your husband to mostly or completely disengage." A few of them told me they were divorced and blamed their small children for being the cause.

My shock and, I admit, disgust, must have been all over my face. One of them asked me if I was overwhelmed, and I should have kept quiet, but I couldn't. I said I thought it was really gross for them to blame all their problems on their kids. If their husbands were deadbeats, that wasn't the kid's fault! Hating your children isn't normal, and it's a sign something is wrong with the parent, not the child. They got cold and one said "a year from now you'll be embarrassed about how arrogant you were. Things will only get harder, and you'll realize what an ass you're being."

I left because I knew there was no point in staying. I also decided I didn't want to see that specialist anymore. When I called to cancel my follow-up with him, he asked why. I said I was going to find another specialist because he recommended me a toxic group. He said that group was for "venting sessions" not medical advice and explained it was supposed to be a form of stress relief. I just cancelled and decided not to argue further.

Part of me thinks I was an asshole to those women, that I gave them the same lack of empathy I saw them give their kids. Another part of me is just completely freaked out by them. Was I an ass to those other mothers?