SO MUCH PAIN: TOO MUCH STRESS: NO LIGHT AT THE END OF THE TUNNEL

I sit here alone tonight and it has been great.  Just my puppy and me.  Not having to deal with the stress of my problem.  The pain and stress of my son's death is enough to bear, but so much more stress is being laid on my plate, sometimes I just don't think I can make it through.  I get not rest. Up down all night.  I can't remember a good night sleep forever.
What to do when your husband's family who are healthy with no problems just keep adding stress on your life,  What do to when your mom (who I truly love) but only thinks about herself and thinks me and my sister are suppose to fix it.  She tells me she cries all day cause she is lonely.  I tell her I cry all day and she goes why. Gezz mom, I just lost my son, her grandson.  It's like she don't even care that Ken is gone.  
I know right now there is nothing I can do to help her now, my pain is too deep, my stress is too much.
Next all I do is argue with my husband about his kids who are 35 and 39.  Who have treated me so bad.  All I ever asked for was respect.  I don't care if they like me. I have never done anything to them.  Even when I flew them in for what was their last Father's Day with their grandfather as a surprise for my husband, they said I did it cause I was in trouble with my husband and I did that to kiss his....
Well, I can tell you, I would not spend one penny on someone if I am upset at them.   They took what I did as something to be special into a monster of a thing.  I paid for the tickets, I planned the surprise, but they just said things that were not true.  Now years have passed and they still don't stop.  They are so selfish, so mean about others, it is not just me that they do it to they do it to everyone.
In Oct after my son had lost his ability to speak due to the cancer, a letter comes 5 pages of how horrible I am, how my husband is choosing my family over them, none of which is true.  Before I met him and married him, I spent all my holidays with my son. After we married we split up the holidays.  We would either go to VA or go to FL or the other way around 5 times a year.  We didn't take vacations, we visited our kids.  But to hear his letter we never visited.  The letter is about going to AL to see my son who had the cancer.  I had not gotten to see him since Feb because of my husband heart surgery.  Now my son is gone, i can't talk to him any longer and see him or touch him, while his son who has not called hardly all year now calls and it upsets me everytime. I think I am either ready for a divorce or my husband stands up to his kids and tell them they are to respect me.  They owe me an apology like I would ever get it.  But it is hard for me to believe that they are so cold that they can't even say they are sorry about my son's death.
Tonight, since my husband has been gone, my stress has been less. I am tired, I am stress, i really don't need the extra stress. So I don't know what to do.
Tonight i watch a movie while he was gone "MY Sister's Keeper".  It is a good]]]]]]]]]]]]]]]]]]]]]]]]]  The movie reminded me so my son cause it's about cancer, but it is really a lot like it is looking for something to keep you child alive.
I was not sure whether to watch it or not, but did and it was okay, I felt it showed a lot of what a mother goes to to try to save their child from death. 
I have no answers tonight, I have no comforting words, I feel I am of no use to anyone right now not even myself.  I don't know how to deal with all the stress
To me the most important thing is I have lost one for my children and every things else is in the way.  Sometimes I feel this stress is getting me to the point of no return, but where that is taking me I do not know.  I am too tired to know anymore.  Maybe I want to get it over with.  So what choices are there in getting it over with. I have no answers, I am just tired a different tired a stress tired.
Sorry to be so glum tonight.  It is just where I am.
Sandi