Brief background, altho I have posted about this before - my husband has become good friends with a woman at work. They work in different offices in different parts of country but for same company. He trained her etc which is how they met and they meet up with work eveyr month or so. They share a hobby in common and always go to lunch or for drinks when she's across at his office. She's a lot younger than him and is really stunning looking. She is married with children (as are we!) I've been very jealous of her and anxious about how much hubby seems to like her. He emails her several times a day including when at home and basically none of it is work related, just chat. He said he likes her tons and they are good friends. I've snooped a lot and never found anything dodge but all the chat seems a bit flirty to me not because they are explicity flirting but because they so clearly like each other and bounce mails back and forth. Not texts as far as I can see although hubs says they chat on the phone at work a bit.
Anyway, I've met her a few times at social events but I've kind of snubbed her and not been very friendly. 
Hubby mentioned that she and her husband and kids are coming to our area during half term to see friends and I've invited them all for dinner. I'm doing it as I want to see her and hubby together and I also want to get to know her. Feel if I can make it all 'above board' with us all friendly together, it will take any excitement out of it for them, or mamke it less likely to develop into something.
I'm worried now though as since they accepted the invite hubby has been bouncing around like an excited puppy. He even talked about what he's planning to wear?! I worry I'm facilitating something I should be shutting down. Should I cancel?