Cindy....he may just feel obligated to go to the work Christmas party...don't try to read his mind. What matters is that He asked YOU to go with him. As for the friends, he may feel uncomfortable at the moment around your mutual friends, given the circumstances of your marriage.
As for spending the night, get a babysitter and don't tell the kids what you are doing...they don't need to be privvy to your sex life...but shoot girl, go get you some! He is your H after all...and it could be the combination of holiday cheer and intimacy that brings things really together for the two of you. If it doesn't work...so you slept with your H again...big deal! No shame there.
Don't start second guessing him now....go with the positive...
Or ignore what I've said all together...lol...it's up to you.