I'm going to apologize in advance for the length of this post. It will be long
My FH parents are divorced and have been since he was 14. I don't know the extent of it as he doesn't ever really talk about it but his mom has constantly bad mouthed his dad and his dad's family for as long as I can remember.
His dad has since remarried and his mom is in a relationship with another person and has been for almost 10 years. His dad has also seen the havoc that his own family caused on his first relationship and has said things could have definitely been different if he had seen that in that relationship. Since his dad is remarried and moved on, we have had a touch and go relationship with him. I've been pushing my fiancé to get his dad more involved in our lives as I truly believe he should be. His mom on the other hand, doesn't seem to have moved on. She has always been very controlling and always wants my FH to be around her. She gets mad when my FH doesn't come around or things don't always go exactly how she wants them. I'm already dreading holidays as I have a big family and am very close with them. My parents have already said that they will just work around whatever we need to do. Especially when we decide to bring kids into the picture. Another topic for another day.
Both his mom's side and his dad's side regularly trash talk the others. It's very frustrating to me as I have a very big and close knit family. I understand that not everyone has this experience and it's not always possible with every family. I want to involve both my FMIL and her partner as well as my FFIL and his wife as much as possible. This is a celebration for both of our families and I'm at a loss at how to even begin to navigate our wedding day if there is a possibility of conflict between my FH parents. I won't even touch on the majority of his dad's family disapproving of us because we already live together (we've been together almost 10 years). I know I need to talk to my FH about my worries but I don't know how to bring it up so he doesn't think that I'm attacking one parent or the other.