I posted fairly recently about finding out that my very recent ex and someone who was a relatively recent but promising friend (I don't have many) who I had confided in about the awful breakup, were in some sort of flirtatious contact. I have also been dropped from the school mums nights outs with her and her group.
He has been adamant that, despite the messages, nothing has happened and she has just text me explaining how their meeting for a drink last week (I found this out accidentally) was totally innocent and how she knew it looked suspicious but it definitely wasn't and asking me to go out with her sometimes.
I want to tell her to go fuck herself.
But I am going to ignore and delete. That's the right thing to do isn't it?
For context, I know many will think I have no 'right' to feel upset but ex and I have been getting on great and spending lots of time together and I was even very tentatively thinking about the possibility of us working out our issues and he had said a few things that suggested he felt the same. I feel betrayed by both of them, ex-DP moreso as he knows how much I struggle with friendships and he has helped fuck this one up for me.
Right now I'm basically in a cycle of making myself look like a well-dressed confident badass on the school-run in case she sees me and spending the rest of the day depressed and crying 
Should I reply or leave it?