Hello HV. Obviously I know your story and because of that, I winced when I read some of the posts on this thread. Few people leave a marriage if they are happy and there is no-one else on the scene, but it's frankly laughable that people don't leave marriages that they were perfectly content with, before they met someone else. The presence of a third party is absolutely the material fact here. There are sadly huge numbers of people who convince themselves that the new person is their true love, until the next new person turns up, that is
.
You've got DCs and your MIL is their grandmother. I absolutely understand why you feel short-changed by her inability to enquire about your well-being, but unfortunately a lot of people are absolutely hopeless in these situations and hide behind doing nothing, or communicating remotely by text.
Because of the grandparent relationship, I would be inclined to be open and honest with your MIL, either by phoning her or seeing her. Tell her that you've been disappointed by her reaction and give her the opportunity to explain. With your friend, take a similar line. Explain that you understand why she wants to stay friends with both of you, but you'd rather she was honest and up front about how often she sees your H. This gives her "permission" to be open about their friendship.
In my view, your feelings are entirely understandable. Because of my knowledge of your situation, I know that you are justifiably angry about the cowardice of your H and the years of secrets and lies. I am very glad to see you write that you won't pretend otherwise - that is healthy.
I find that unless this has happened to someone personally, people are remarkably insensitive to how long it takes to discharge that anger and disappointment. 4 months doesn't even touch the sides, frankly. If you ever get any sense from people that you should have pulled your socks up by now, challenge it most vigorously. Your whole life was turned upside down this year and everything you'd believed for years before that was cast asunder.
You haven't fallen apart. You've carried on working in a very demanding job, you've cared for your DCs virtually single-handed and you got yourself some good therapy. You're doing just fine, but you are entitled to still feel angry, sad, disappointed and any emotion you can care to think of. Don't let anyone tell you otherwise.