You would probably have felt uncomfortable if you had gone. Your GD might have felt the tension between you and DIL. Or the tension from DIL's family.
Please don't waste a moment on regrets. Your decision was very carefully thought out. For you it felt right. Therefore, you won't have to worry about DIL or her family talking about you and opening old wounds.
Why not put it behind you and enjoy your DS and GC when they visit?.