I've been seeing a guy for a few months now. Things going well, we have similar interests, kids are similar ages, all trundling along nicely.
A couple of hiccups along the way but nothing major. He does have a tendency to shit down and not discuss things if we have a disagreement, but each to their own. I'm a big talker, he's not.
Anyway, I found out last night that he is still married. Legally separated but technically married. This is the first I've heard about it. He's never actually confirmed he's divorced, but after 6 years, I had assumed that they were. It's been absolutely clear from previous conversations that this has been my assumption and he's never put me right. Until last night.
When I asked they're not divorced, I got the answer "I don't know" Which is the kind of answer I get from my 10yo when he's asked an awkward question that he doesn't want to answer.
I pointed out that I was sleeping with a married man (unbeknownst to me) and that wasn't a position I was prepared to be in. Has it ever been discussed or will it happen at any point in the future? "I've got no plans to"
I told him that found it odd after so long to not be divorced. And to go through the rigmarole of legal separation but not take the final step. He told me it's perfectly normal and he knows LOADS of people in that position. Erm, I know fucking no one in that position.
We were going round in circles so I asked him to leave. He then said he didn't know why I was so bothered as it's got "nothing to do with me"
My boyfriend's marital status is nothing to do with me 
Please reassure me that I'm not overreacting?! It's not acceptable to not tell someone you're still married is it?!
To avoid drip feed, I have always had a niggling concern over their relationship. They're very close. However I am an anxious and quite insecure person so I've tried to keep a lid on the bubbles of anxiety about it, as I'm aware that I have a tendency to be a bit unreasonable about things like this
Thanks