The OW set me up for a confrontation, and like a fool I walked straight into her trap. I understand your feelings OP, I loathed my husband for what he had done to me and the DC, but I felt positively murderous about the OW. Like the OW in your situation she did the social media stalking etc, and she also worked in the same place as me and my H so it was hell on earth.
She began going to the same gym I went to and would smirk whenever she saw me. I kept it together for about a month of this, changed attendance times etc but she always seemed to be there when I was. Of course my H was still in touch with her, despite his assurances to the contrary, so she knew my every move
..
I lost it one day in the changing room - didn't lay a finger her although God knows I wanted to. But was pretty blunt about my opinion of her. She laughed and I realised my idiocy - I had given her what she wanted. She went straight to the police, claimed I had pushed her hard and threatened to kill her. I had done neither of those things but I still ended up being arrested by appointment. I was bloody lucky; a woman who was elsewhere in the changing room confirmed my version of events, and I was able to show the police the taunting emails the OW had sent me in the weeks leading up to this. But I still formally warned against 'harassing' her (albeit she too had the same warning from the Police). I cannot begin to describe the humiliation of being in that bloody police station.
Mine is an extreme case, OP, but please, please don't go down the route of any kind of confrontation. Don't give her any door into your heart or soul. Don't be me because all it does is allow her to think that she matters in some way. She doesn't, she is irrelevant and the only important people in this are you and your DC.
And incidentally, I don't believe you have to forgive your DH either at this stage - yes, you can move on and build a different relationship with him, if that is what you want, but forgiveness can take a long time coming, if ever. A friend of mine whose DH has a very long-term affair says that she has to forgive him every day when she wakes up, and that affair ended 15 years ago. For you 