Well, how you and your H used to function (you chatting with him while you were working at home and he still lived in the home) doesn't really matter now, does it?
Your H changed the status quo by moving out and ending the marriage. IMO that eliminates the perks he once had and one perk is chatting with you or having a "quick talk" while you are working. You are now a single woman on your own and your priorities are different. It's not rude, it's reality.
A quick hello is fine IMO. Your H is good at telling you what he needs/wants (my ring, a divorce, is my name going on the gift and blah blah blah) and somehow not seeing anything different from you.
Be fabulous, be busy and keep your focus on what the priority is during your workday (WORK!).
