I went a very long time without speaking to my STBX, and during that time if he HAD to speak to me about something it was ALWAYS an argument. Wether there was a point to argue or not. It was awful and I did/do miss him as a person.
I can't speak for your sitch, as I don't know your H, but I think it was best for me to leave STBX be. He came around in his own time in being civil to me again.
We don't really ever TALK about anything anymore. It is all about the kids or the D. But it is nice not to be yelled at.
The silence is miserable but somewhat peaceful. I learned to live with it. But in my case STBX is across the country and I don't have to see him on any kind of regular basis. I can see where it would be more difficult since you do.
I'm sorry I'm not more help. Just try to focus on you and D7. I know it's hard but I don't know what else to do.
As for the settlement, do whatever you need to do to be financially secure. If it means fighting him over the $300, if it's worth it do it. I negotiated with my STBX, we agreed to everything then when he talked to his L he changed his mind and we ended up going back and forth. Finally, he gave some and so did I.