Destiny, You can casually mention that you are going out for drinks and then offer up an invitation....but do not expect him to say yes. Leave it up to him if he wants to go.
I think your h is getting vibes from you about your anxiety and the fact that you are nervous and waiting for the other shoe to drop. Just be yourself. I understand that the ow is in the back of your mind, but you are allowing her to have a space in your head and she's not even paying rent. You are allowing her memory to dictate everything else in your life....let it go! You've got to make an effort to block her out and focus on the here and now.
Destiny, if your h is going to leave or go to the ow, it will not matter whether you are doing things that you use to do while he was away or not. Stop hovering over him! Live your life and get back into doing activities that you enjoy. You have to understand that just like an addict, until he hits rock bottom or hits that dark wall, he will not seek assistance and you can't help him. He will need to make the decision to seek assistance, i.e., no matter how much you try, it will not work. If anything, maybe you need to be talking to someone who can assist you in learning how to deal w/him and his depression. I created a posting many years ago that was called "highly recommending reading materials". On that thread, we posted a lot of good books on depression. I would suggest that you begin to read up on depression so that you can have a better understanding of what is going on. Depression isn't just about sleeping, eating or lack of eating and feeling blue...it goes much deeper than that.
Destiny, today is a new day...get out there and do something fun for yourself. It is time to take back your life. Stop worrying about whether or not you are doing the right things. Life is far too short and trust me, your h may very well appreciate the fact that you are focusing on something over than him.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.