My son and his family are going to see my ex and the OW 

I have been dreading the time my children would have to meet the OW. I use to be so full of anger and hate. How dare she want to be apart of my children's lives. How dare she want to meet my innocent grandchildren. She did so many evil things to me as did my ex. 
Now the time has come. My ex put a stipulation on the children seeing him they could not see him without meeting Tracy. 
I am not upset like I thought I would be. My concern is for my son and his family. He knows what his father did and allowed Tracy to do. When my son left here he had tears in his eyes and said "Mom I don't want to hurt you more." He did not hurt me his father did. I also look at it this way if my son was not going through this it would mean I would still be married to my ex. My 38 years of marriage was full of abuse and cheating. I am so thankful I am not married to him anymore. The pain and heartache I went through was worth it all not to be with him. My children are adults I cannot be a buffer between them and their father all I can do is pray God give them peace, strength, and wisdom. 
In away I feel guilty for being thankful that I am no longer in that marriage, for as long as I was there, I was able to be a protect them from their father. Keep my children in your thoughts and prayers.