Divorce is never easy. There are good reasons you wish to divorce. but divorce rarely only involves one other person. While you may divorce your husband or wife, there is an entire social network that will be implicated in your divorce.
Your children can be particularly thorny as a joint or shared physical custody or visitation arrangement with your children's other parent is likely to keep them involved in your life for the remainder the years until your children turn age 18, and potentially longer if you are jointly collaborating on their college education.
You can minimize some of the strife that could develop from this aspect of your divorce by working together to develop a comprehensive parenting plan that will both meet the needs of your children at this time and be flexible enough to allow the necessary changes to the arrangements as your children grow.
Another concern is your in-laws. While there is nothing to say that you could not continue to maintain a relationship with these individuals. You may have grown quite close during the marriage. For others, it may be "good riddance." But if you developed emotional attachments to your in-laws, you should approach the issue with care.
Before the divorce is final, you should not communicate with them, as their interests are likely to be "adverse" to yours and your attorney is likely to counsel no contact except in certain special circumstances.
If you wish to explain yourself after the divorce is final, you need to be respectful of their pain, especially if you initiated the divorce and they "blame" you for the hurt you may have caused their son or daughter.
You may have no expectations of your relationship returning to "normal" after the divorce, but you should expect they may either not respond or may respond cooly to your communication. But they are likely to remain involved with your children, as they will always be the grandparents of your children.
In some rare cases, they may understand; after all, they may know your ex- rather well and recognize the problematic nature of their behavior. No matter the outcome, you may need the emotional closure such communication brings as you move on with your life.