I am so sorry for the loss of your husband and for the intense grief you and your son are experiencing.
Losing a spouse or parent is hard enough. Losing a loved one to suicide adds another layer of complexity to the grieving.
I hope you have supportive family and friends who can help you during this difficult time, but it would also be very beneficial for you and your son to seek out grief counseling and grief support groups that are specific to people who've lost loved ones to suicide.
The American Foundation for the Prevention of Suicide has numerous resources including lists of in-person support groups for people who have lost loved ones to suicide. Go to afsp.org to find the closest meeting to your location. They also have online grief support groups if you cannot make in-person meetings.
Save.org and suicidepreventionlifeline.org also have many resources for survivors.
There is an online booklet called Help and Hope: For Survivors of Suicide Loss (just type this in google search) put out by the Suicide Prevention Resource Center.
There is also a new book, just published this year called Life After Suicide: Finding Courage, Comfort, and Community After Unthinkable Loss by Jennifer Ashton, M.D. Dr. Ashton is an ABC News Chief Medical Correspondent who lost her ex-husband to suicide. She shares her personal experiences and that of her children as they grieved this terrible loss. It's an excellent book that I think will be helpful to you. I don't believe it's in paperback yet because it's so new, so if you don't want to purchase it, you could get it from your library. I highly recommend it.
Please make an appointment for yourself and your son to start talking to someone, search out the support groups, and start reading through the resource materials. It's so important that you and your son do not blame yourselves in any way.
There is no one single thing that will help. It will be a combination of things: time; reaching out to others; getting the support and help you need; willingness to take it one day at a time; accepting that some days will just suck, but you keep moving forward anyway; accepting that you are not responsible for your husband's choice in this; learning to live and laugh again.
You and your son will live and laugh again. I know from personal experience. It's been 35 years since my father died by suicide. I still miss him. It took time, love and support from friends and family, and professional help, but life is good, and with acceptance of the things you cannot change, comes peace.
Wishing you strength and peace.