I too have lost a son and while I don't know the pain you are experiencing directly, I can at least relate. My son was 28 when he committed suicide, so we had much more time with him, but the pain I felt and still sometimes feel is the worst I have ever experienced. I've blamed myself for the 8 years since it happened, but I really think the earlier post about President Monson is wise counsel, and I hope you can and will take it to heart.
If you ever want to talk to someone who has had some experience with the loss of a child, send me a message and I'll respond. My older brother lost a son to cancer and just being able to talk with someone else who has experienced this kind of loss was very helpful to me. It's probably a good idea to find a good counselor for each member of your family, and especially for yourself. Group support sessions can also help. The feelings will be very raw, but catharsis is a necessary part of healing for this kind of wound.
I can say that the pain and feelings of guilt do diminish over time. May you find rich blessings from the Lord and from family and friends.