I don't think it is petty, but I agree with those who have said that being in rehab is really difficult and the first couple months of sobriety are hell.
I can understand how you feel, wanting your husband back, but the best way to get him back is to allow him to get his head on straight. Which is not to say that he should get an indefinite amount of time to not participate in the marriage. However, when he is in rehab, he definitely should be as focused on that as he can be. Those people in rehab who worry too much about taking care of things on the outside were those who did not do as well when sent back out into the world, from my experience.
I don't know how much this helps you. One other suggestion, if you haven't already done it, is to check out AlAnon for yourself. Other people will understand exactly where you are because they've been there too.
I wish you and your husband the best. That he is in rehab and working on it is a great thing. I hope for both of you it sticks.