I seriously understand your anxiety over this. All I can offer is that I know of no place where there is any suggestion in the scriptures or through new revelation or the writings of any modern day prophet or apostle that indicates that there will be any dating or searching and subsequent sealing of any sealed/married man in the celestial kingdom to any other woman that wasn't first sealed here by that person or by proxy. In short I personally do not believe you will have to sit in your new celestial home right down the street from our heavenly parents, full of tension and anxiety, while you husband goes on a celestial date. That doesn't sound much like heaven to me.
But lets say I'm completely wrong. If I am wrong then there is something that you and I don't understand yet. If it is the case that somehow your husband will be given or assigned other celestial partners then I would guarantee you that it will only happen with your complete support, love and understanding. I seriously feel that God loves you and will not create a celestial circumstance that causes you pain. I do not speak for the church. I am not even close to being a General Authority. But I do speak as someone who studies scripture and the words of our leaders, who tries to live a Christ-like life and has a Temple recommend in his pocket.
I hope this helped.