Andrew, I've been so wrapped up in my own sitch today that I hadn't had a chance to check on you.
Why don't you feel you can hug/kiss her? Does she reject you when you do this?
Intrusive thoughts--completely understandable. Come here to the board and vent.
If you feel alcohol might make you behave in anti-DB ways, don't drink! I haven't had a drink in 14 years (my H has never tasted alcohol) and I tell you it's a lot better. You can save the calories and have a bowl of ice cream instead :-)
I would just be cool and fun around the SIL's. Give them space when they want to be on their own. Don't bring up the M problems if possible. Whatever you say to them, you should assume will be said to your W.
I hope I helped a little. Thank you SO MUCH for being there for me today when I needed it the most.