My (28F) best friend (30F) kissed my husband (28M)

Throwaway.
My best friend has been going through a tough period in her marriage and both she and her husband have separated for a time (both with their fair share of indiscretions that initiated the separation and have occurred since).
My husband is also best friends with my best friend - we all met at the same time and they have a lot in common.
Between our family life and our friends sorting out their marriage, my husband didn't get a lot of opportunities to be there and really help our friend through her issues, and they hadn't caught up in a long while.
Given that I had just had a night out with her, I said he should definitely go hang out with her and spend some time. Maybe he could offer advice or support that I was not able to give. So he went over, and I stayed home with our daughter.
We are all big drinkers, and so it wasn't surprising to me that he arrived home very late and in a somewhat inebriated state.
The next day, we were spending a night away for my birthday, something we had planned in advance. It was a great night.
We come home the next day, it's late, we're doing the bedtime routine for our daughter when we get an unusually hostile text from our friend, the husband. We try texting him, we try calling him, nothing.
Maybe two hours later, husband gets a text from Best Friend saying she'd "told husband about what happened. He thinks it's best to have space from you two and I do as well"
I look at my husband, confused, and he then tells me that best friend kissed him when he was there. He admits to half kissing back for only a second before noping the **** out of there and getting an uber home.
I'd like to make it really clear that I'm not mad at my husband for this, and while I obviously am upset that he "half kissed her back", I don't believe he is as much at fault as he seems to feel he is. He's a genuine man who loves me and loves his family, and he has been beating himself up constantly since this happened. He went there to comfort and offer support and advice to his best friend, not to kiss or to be kissed. It has made him question his value and worth as a husband and a father, and he doesn't need to. This makes me angry.
I understand why he didn't tell me straight away, and I am not mad at him for that either.
I'm confused as to why my friend/best friends husband is somehow blaming ME and has written me off completely, when I was one of his biggest supporters while his own marriage has been crumbling.
My best friend hasn't said a single word to me since I found out. Not a hint of an apology, no explanation, nothing.
They are both saying they need some space from my husband and I as if we are the ones who wronged them.
I feel angry and betrayed. They have been our family for nine years. I love their kids, my daughter loves all of them. I tilt between wanting to burn whatever remaining bridges are between us, remove them from social media, etc and reminding myself not to be so rash and to wait a little longer.
tl;dr: my best friend drunkenly kissed my husband and now both she and her husband, also my friend, have cut us out and are acting like we wronged them.
edit: a word edit: clarified, added sentence


Source.

Riiiiiiiiight, for only a second, huh?

Hes beating himself up sooooo bad, but yet didn't say a word to you about it and probably wouldn't have. You think he left immediately? How naive. I am Queen Elizabeth too.

It's probably best for y'all not to be friends...at least for a while. They are probably acting distant because the **** is awkward lol