Paige,
I'm so sorry to hear about your devestating losses! My heart aches for you guys. I'm so sorry to hear that both sides of the family are failing you. I'm delighted to see that your husband came around and is supportive of you. You guys need each other cause it appears you guys have no one else to turn to. I would say that your marriage should be a top priority in both of your lives. In the future if you feel like it's not doing too well then work on it - seek help. Stay strong.
My advise to you regarding your mother. RUN!!! Anyone that is so toxic that she has influenced decisions of suicide should be considered dangerous!
If she continues to try to contact you - seek legal counsel - get a restraining order or something. You need to protect your kids from this menace. If you become strong then she will move on to easier targets - your kids. (My N family were beginning to make my children feel inferior)
( kids have enough to deal with today, without their family trampling them down)
Regarding your families. Cut them all off. If both of your families weren't supportive during your worst hours then when will you ever need them?
You need time to heal. My God, you and your husband have been through hell and you need to give yourself plenty of space of time before you even "think" about having to DEAL with N's. They kicked the wounded when they were down. Who needs a family like that?
It is not wrong for you to have to protect yourself and your children. You wouldn't let a stranger come in the house and hurt you or your family? Then why let toxic people into your life and hurt your family. It is the same thing regardless of WHO they are and whether they yield physical, mental, or psychological harm.
It will be painful to seperate and you will go through a lot of anger and frustration, grief, and sorrow ( perhaps ) but it will also be a relief, a peaceful time for you guys to re-group and grow stronger. To heal. To learn about who you were dealing with. (N's) To learn that you were not to blame. That your not "bad"
Regarding: "is there another way?" I think you should go with your instincts. If your instincts are telling you that you need to protect you and your kids, then that's a big red flag telling you something isn't right.
God bless you guys.