NO!! You are NOT wrong, his behaviour is manipulative and abusive. He hasn't thought about you or your children once in his selfish escapade so don't feel sorry for him, don't listen to his attempts at guilt tripping you. Time for you to turn the tables and serve him a nice dose of karma. He can't have all the cakes and eat them. You are putting yourself and your children first, he isn't. Get a solicitor and let him know further communication can be made via them. Apply for CSA to take the money for the children (including backpay since he left) directly from his pay. And don't let him get you down anymore, he is an asshole, a massively selfish asshole and he doesn't deserve any leniency now. NONE of this is your fault.