Guava,
You sound like such a giving and wise mom. You really seem wise with how much you can control and jumped in with two feet to help at the passing of your FIL.
May he rest in peace. Hopefully you will be able to have MIL over for grandchild time regularly? You sound more grounded than her kids. It meant the world to them that you had them over at Easter. You will probably cherish that hug the rest of your life. You are strong and present. Something addicts can't hack.
Peace to you and yours.