Hi mamab and welcome. I'm so sorry you are in pain right now. I don't think there's a magic "fix" for grief, though heaven knows I've searched for one for years. Just my experience - grief is an ocean and it comes in waves. There are times when the waves are just lightly lapping at your toes, and other times when it's a doggone tsunami. After over 2 decades of living with- grief in it's various stages, I think the most important thing you can do is to take care of yourself, physically and emotionally, and nurture your relationship with- family, friends, husband, and your kids. I also think it's important to allow yourself to grieve - don't fight it. Grieving doesn't mean you love your son less; it's not a poor reflection on you as a mom or a person. It just is. Again, just my experience, but fighting it made it *much* worse.
I still have days when I mourn the loss of what I expected, what could have been, when I am just heartbroken over the challenges 2 of my kids face. I'm better about just going with the flow and then picking myself up, brushing away the tears, and moving on. It's taken practice to figure out how to grieve in a healthy manner for me. Intermittent counseling over the years has helped.
It *will* get better... and then you may have periods of time when it gets rough. I just take it one day at a time until I feel like I'm drowning - then it's an hour at a time or a minute at a time. Knowing that it will pass does help, just a smidge.
Gentle hugs to you, and again, welcome.