The renewing of your vows is a great idea...you could have a picnic thereafter...but it would symboloize a brand new start for both of you.
I'm very sorry your inlaws have treated you both this way...however they were wrong, and I wouldn't fret in the least about sending that email...your only human and you did at the time what you did in defense...you have learned that you cannot get anywhere with these people, and how sad for them...
Your never going to get anywhere with these inlaws and they're extended family...resolve that in your mind and go forward...you and husband have each other and that is all that matters...what I have learned is, when a son gets married, his wife brings him a new life...and he needs to consentrate on that...yes, it would be nice if you could all get along, but that unfortunately seems impossible.
I feel badly for both of you, and yes, it is very sad for him, however, the more contact you would have with them, the more hurt and anguish you would experience, therefore, change your attitude and know your both doing the right thing for your self preservation.
Please know your in my thoughts and prayers...this can be worked out...unfortunately, inlaws are missing out on so much, however, they created this problem not you...your better off without them in your lives...and it's ok to feel the way you do...thank God your still together.
Hugs
Creme