The tablets won't turn you into a zombie - they will just help you maintain an equilibrium.
Have you read No More Mr Nice Guy? I can't remember. I know it's a guy book and a lot of the men on the boards have found it VERY useful.
If you can't sleep at 3am then get up. There is absolutely no point in staying in bed tossing and turning and thinking destructive thoughts. That's the time to get up and do your Sudoku or other things to distract you. Go for a drive and take some really wonderful early morning photographs. Then hopefully by the next night you will be so tired you might sleep better.
Have you started reading that 'Learned Optimism' book yet? I found the first half quite daunting but the second half really showed me the way to go and offered me hope.
Stop the paralysis of fear, breathe and start doing things that YOU want to do. Your W is lucky to have you and that's the way you have got to view it. A lesser man would have kicked her to the curb by now. Don't act as though she has all the power. She hasn't - it may feel like that but I bet she is scared inside too.
Even if the worst came to the worst and it doesn't work out with your W, (which btw I don't believe will happen in your case), there is NO WAY you would end up by yourself. You have way too much going for you. It's the good men that get in shorter supply as we age, not the women. Your W is the one that should be scared about being lonely, not you. She would lose the respect of her family and alienate herself from her safety net .
You keep at it - you have been doing so well.
Saffie me 46 H 46 M in 1986 D20,D18,S16,D13 H's A 01/05 to 07/06 H recommitted to M 07/06 renewed vows 09/06 Going from strength to strength
