Mother remarrying

My husband and I have a daughter Alhamdullilah and Allah has blessed us with twin boys who will be born soon In Shaa Allah. I am stuck as to what to do. My mother who has decided to marry again this will be her forth marriage but this choice has made both myself and my sister very unhappy we are heartbroken about it as she has before gotten married without our knowledge. Now this time she has told us that she made this choice and did not ask our opinion or how we felt. I know it is Sunnah to be married, but this decision has caused so much pain to my marriage as well as my husband is always saying really bad things about her and I am constantly having to pick sides. I cannot find a way to solve this I am suffering but cannot explain to my husband that she is still my mother and I need to respect her but what if I can never accept her decision to marry again. I don't want my children to suffer as well and I am afraid this will cause her to not meet with her grandchildren. May Allah guide in this difficult time. Based of the above. Is what my mother is doing correct by choosing to marry over the heartbreak of her children?