Is it possible for you to take your kids and go to where your friends are? It's a shame that the visit has had to be cancelled since I bet you could use friends and support more so now than ever.
Do NOT meet up with your MIL. It will leave you feeling worse. My MIL told me after AH was arrested, spent 4 days on a bender etc... that I "expect too much" and need to give him a break. So, your MIL's suggestion that you weren't loving enough is just another b.s. line like those my MIL said. She is enmeshed and an enabler and wants to blame you just like your AH does bc otherwise they have to face the truth and clearly they can't do that.
Get a sitter and go out with your friends... You need to for you.
I have had to deal with the people I thought were friends who made it clear in subtle and not so subtle ways that they couldn't imagine AH being as I described and who clearly believed I was exagerrating. The real friends I have are ones who I don't have to go into details with and who know exactly what is going on bc they know me that well.
I am sorry things are so hard. So many of us have been and are in your shoes and we understand...
xo