You need to seek forgiveness and pardon from them. If you are unable to do that then seek forgiveness from Allah to forgive you and them and keep praying for them.
If there are genuine problems with your in-laws then you can discuss this with your husband with the intention of finding a solution. He may be able to intermediate and speak to those in-laws to find a common ground or way to reconcile differences. By not discussing these issues it can become worse, so it is good you are thinking to do so.
Just make sure that when you discuss these issues, it doesn't exceed the limits of the necessary matters. For example if one would starts insulting them then it could lead to ghiybah or mention unrelated matters
May Allah grant you success