Fab - you are me 4.5 yrs ago!
Your story - mirrors mine so closely, except DCS were younger.
Fuck everyone you do it for your kids, you do but it does not mean it is easy, fun, pleasant, likeable or anything else..It sucks the cock of effing death every day you do it. MY DCS were much younger and not once did I slag her or him off.
You are doing so well. Like you the OW, was ex best friend, who used her knowledge of me, to manipulate situations and cause immense private grief.
The argument that it is he who betrayed you and not her - pisses me off. He did and I have moved on - do not want him back and my anger and hurt is still there but we have to have an amicable working relationship for the sake of our DCs. She betrayed me aswell - as a friend and the continuing justification of her actions and the need to hurt you going forward - just demonstrate her insecurities. The using my kids as a weapon in her war against me, is unforgiveable. Slagging me off on social media etc .
Criticising my child care decisions, ie, put DCS in nursery 3 days per week so I could work, then got a childminder for drop off and pick ups three days per week. Other 2 days I worked butdid flexi time to do the school runs.
Keep going your DCs will get it - my eldest does and is 9.
My friends kept telling me what goes around, karma etc and finally a year ago - it did!!!! After a fairly stormy tempestuous few years - he walked out on her!
She has a poorly paid job, has always lived off her men ( Third marriage/long term relationship she had wrecked) and is trying to rip EX off aswell - karma comes as he failed to pay maintenance for 2 yrs!
I am financially independent, can afford to take my DCs on holiday off my own finances, live well but not excessively and have two of the most loyal, loving, caring DCs who I absolutely love to bits.
I am in essence free - was lonely- v slowly venturing into the new man scene, have cried, laughed been so bloody tired, angry, hurt, disappointed everytime he failed to see his DCs, curled up in a ball when he took them on holiday with her once in 4 yrs and cried - have had hugs and kisses and cuddles from my DCS when they realised I was "not being you" and learnt to organise, work like a dog and smile.
OMG I can smile!
Keep it up - you are better than her and know it!