I agree with all other posts. They will do/say anything to suck you back in. I also get very scared when legal terms, and threats implying I'm a bad mom are thrown around. They know this is so hurtful to us. They know we love our kids so much, would leave our spouse and start all over for our kids. So they use this as our "weak" spot. Its like a form of bullying. It has it's impact, he knows it, and he tries to scare you.
I loved the comment about wanting to look like good dad, but not actually being one!!! So true.
I also try to limit the communications. I prefer emai, that way it's easy to print & you have record for court. We only communicate about kids, otherwise we are nc. I also anticipate him turning nasty in court and being accusatory. He's still at a place where blaming me is easier than facing the demon. I plan on printing and bringing every email to court. You are right to realize you were "too nice". I think you were. But don't beat yourself up. Just learn the lesson. Less communication!
Also, you are a good person with good intentions. For yourself, your kids, and even him. You are not trying to be hateful or use the kids. I believe that if you keep doing what is right and true for you, things will work out. Court is a scary place but the truth will be revealed. You may have to sit through his crazy lies and bs, but you know the truth and it helps to trust that your path will bring you where you are supposed to be.