I really can't offer any advice, but I am hoping some others will.
The choices we make in thought word and deed inevitably return to us in kind.
I don't mind answering your questions at all.
Some random thoughts.........
We were always told that being married is best, because everything defaults to the spouse. But, since my father has passed away, my mom is finding out that having everything joint, has been one big PITA!!! They have literally frozen some of their accounts, until a death certificate is given. Instead of just removing my dad from all her accounts, she basically has to reopen new ones. She's having to wait to get money out of their joint accounts (frozen ones) or other individual accounts (not bank). Then she found out.....had they had separate accounts, she'd just need to be the beneficiary, show up with a death certificate and they'd cut her a check right then and there. Makes you really think twice about doing anything jointly. lol.
I would say that combining finances is a very personal decision. Like I said, DH and I have a joint checking, but because of his spending habits, that is soon going away. I will never have joint credit cards ever again. Would I want my DH on my house loan? I dunno. I mean, if he's basically going to be supporting you for 2 years, then why not? Especially since he has a solid career (meaning layoff is unlikely).
Again, what makes you feel uncomfy? Is it your past r'ship with the ex? Is it because you're having issues becoming 100% dependent on your DH? I think the source of you being unsure.....will answer your question if it's a good idea or not. Also, to a point, it's not like you have to combine anything but the refi....and that he doesnt' even have to be on the house title (I think).