Belinda, as RunGirl says, now's not the time to be making life changing decisions. I'd suggest you visit your GP as they can put you in touch with a grief counsellor (my MIL has finally agreed she needs help a year after losing FIL and is going to her GP for advice today as he offered this almost a year ago) but also for advice on your lack of sex drive as this could just be a symptom of your hormonal changes and could be sorted out very easily which might help things between you and your OH.
As for your OH - if he's had a very high-powered job he's probably feeling a bit lost and hopeless with a lack of direction and most men revert to being small (stroppy) boys when their lives aren't going as they should. Has he got any hobbies or interests that give him a routine? Will he talk to you about how he feels?