I can understand feeling whiplashed. And, were I in your place, I would be a bit pissed at the notion that I could simply resume a relationship as if there was an on-off switch, after being tossed aside so easily. That being said, I have had experiences in the past of getting back with old boyfriends and it working out okay, so I'm not of the mind that you can never go back again. The important thing, I think, is not to assume that you are all still the same people you were, even if it's only been a few months that have passed. And, as far as what to ask for this go-round, I think it would behoove you to ask that the status and shape of your relationship with this man be determined by the two of you only. That issues between him and his wife be worked out among the two of them, but that you and he decide what to do about issues in your relationship. I would try to develop at least a friendly relationship with her, and be sure to express that your needs and emotions shouldn't be taken for granted ever again.
And perhaps I would ask for a "probation" period to see if it will work out. I know that sounds odd, but I would be afraid to give my heart again if there was still a chance it could be jerked around like that again. So I think if you set a time period, like a month or two, where you can check in and revisit whether or not things are going well, for everyone, AND that if his wife leans toward vetoing again, that there be discussion first (no blind-siding) and it can't get vetoed until that time period is reached. Of course, she would have to agree to that as well, but it might give you all a sense of security. Make sense?