God you've really really hard it so hard. Your utter emotional exhaustion really shines through your posts.
I have been through trauma but not so much in regards to deaths in families.
I can only try and tell you the things that worked for me. Some of them may help, some of them may not.
Counselling - I see you're doing this already. Definitely keep going. There were times I didn't want to.leave the house and wanted to cancel my counselling appointments. I was glad I stuck to them though.
Don't be too hard on yourself - accept that you need to wallow and hide under a blanket for a bit. Is there any way you could have a family member or friend take the kids for a weekend? Take their mind off it and give you some space?
Sleep - sleep as much as you need to. If you can't sleep, try Valerian tea. Don't drink it if you need to drive.
Meditate - I found this very helpful. Just to give my brain a break. I still do it now (child permitting). Emptying your mind of all that traffic and just focusing on one thing. Bliss.
Hobbies/self care - try to indulge yourself a little. I took a massage once every two weeks. Did my nails. Indulged my creative side by drawing. Read alot of books. I also escaped for a while in a rather immersive game on my Xbox. Sounds pathetic but it really helped me escape from the stress and anxiety. It helped me escape reliving the trauma as I played it out in my head so much.
Cry - you must grieve. You must cry. You must let this emotion out. I'd imagine counselling is the place you do this as you wouldn't want to do it in front of your kids.
Get outside - whilst it's important to accept the blanket days, its equally important to get out. Get some fresh air. Do it with the kids too. They need it too.
Surround yourself with friends and family - feel that support if you have it. Even ringing them will help.
You have been through so much OP and you really will be in my thoughts. It must feel never ending. Like your XH's family has sucked the life out of you and you have nothing left to give. I'm so sorry you have been burdened with it all.
I truly hope some of this helps. I hope you find some peace, I hope you find some time and head space. I hope you start to get some emotional energy back.
Sending you lots of love and light x