This...sounds very painfully like what happened to me with my ex. I understand what you're going through, and you are not alone.

I do agree it is a huge red flag that he's kept you away from the daughter for so long, but at the same time, he's been a) with you for a decade and b) you've been over to stay with him. I feel like within a decade you'd have been caught by the wife, you know? Cheaters can be good, but they inevitably fall. I feel like 10 years is a little too long for there not to have been a hitch or two.

And yes, 13 year old's can be little PITA's when they so choose to be, bless their hearts. Her age doesn't necessarily mean that she's okay with you dating her dad or that she's okay with the divorce. It's still going to hurt. The only reason I was ever okay with my mother dating my stepfather was because I KNEW my mother and father had ZERO chance of getting back together. That was made clear. My father also remarried when I was young (5 or so? I dunno. My stepmother is a (INSERT WORD HERE), so I'm not throwing too many anniversaries for her, even if I'm starting to get on good terms with my father).

While I will admit I'm giving you the same advice I gave myself in my situation (which worked out less than well), don't give up just yet. You need solid evidence in either direction before you can act. Meet the daughter, and go from there.

Please know I'm praying for you, and please feel free to PM me if you need to talk. As I said, I understand where you are now.

Hugs,
Harley