Thanks guys for your amazing advice
He has actually already suggested a sit down between the three of us, which is great. I'm going for dinner with my metamour soon too, so I know there is good will all around. I guess the thought of us sitting down is kinda scary, too, because if I'm not sure what's been communicated and what hasn't then I don't want to come out with something that she doesn't know, or find that there are things I don't know about the relationship! I suppose, though, that it's actually a very good way to bring these issues to the fore if they do exist and get some reassurance for everyone involved if they don't.
Thanks again for your help, it means a great deal that others know what I am going through!