When this type of thing happens one just wants the pain to stop. Been there. It sucked and took a good year to recover. Why I didn't do myself in? Because I know that the emotional pain without the physical body on the other side is a thousand times worse and there is no fixing things once the physical body is dead.
Best thing to do to help get through the pit of dispair is being out in nature, listening to good music and get the creative juices flowing by doing something one enjoys. Even if it is volunteering to help others out in need helps to get one's head out of the black pit.
My nephew is going through this now - wife is divorcing him - he's got 4 kids and at a total loss. He's dealing with PTS from serving in Iraq which wasn't pretty. To help himself move forward he decided to volunteer helping with a group of kids. One feels worthwhile when they're doing something worthwhile.
Most folks have got a lot of good in them and are here for a reason.
In addition, the best person in my life came into my life after going through the pit of dispair. Just a reminder - don't give up. Hang in there because what one has to offer is needed by someone you may not even know yet.
The truth is incontrovertible. Malice may attack it, ignorance may deride it, but in the end, there it is. Winston Churchill