Should we cancel since I don't want to make my husband upset?

Yes, but no.

I think you should cancel because you need to take a step back and have a convo with the husband about that blow to his ego. That's something I think you need to work out before you give it a second go-round.

The thing about a threesome is that:

1. Almost no one is totally 50-50 bisexual and even if they were
2. No one is going to be equally attracted to both members of a couple, and even if they were
3. It is nearly impossible with the way orgasms work that you could have someone spend an absolutely equal amount of time with each partner.

It just doesn't work like that.

If you keep going down this road you're going to have both experiences, and you may even have both experiences with the same third.

Sometimes it's going to be about you and her, sometimes it is going to be more about her and him, and sometimes it might be more about you and your husband with a helping hand in the mix. Sometimes all in the same night.

The fact that you wouldn't want to continue if what SHE'S into is not what you and your husband want (you basically watching the two of them and involving yourself here and there), that's a problem. Not an unsolvable one, but one you need to hammer out before the deed is done.

The last one was only a few weeks ago. I think you and your husband need a couple more nights where you crack a bottle of wine and sit down and talk about the dynamics of a threesome and how to best prepare yourselves for the next one. Because you've only had one and his expectations for what HE wants are so high, I think you need to talk it out to get back to a place where you can respond to the situation as it is presented to you. It isn't fair to the person you're inviting for her to come in with this strict sense of what you want out of her because her pleasure and enjoyment is part of the deal. She's a person and entitled to participate the way she wants to.

So take a step back, ask to reschedule, and do some more talking. Try to focus on seeing each threesome as its own thing, a contained experience, and less on keeping score about who got to do what. If you keep having threesomes, you'll all get what you want eventually. But you're putting too much pressure on this NEXT experience as a form of compensating for what you didn't get last time and that's not fair to anyone.