Child & spousal support

So I've been going thru a divorce for the last several months and I've been trying to play nice and part ways on good terms. But thrugh our entire marriage he was always a tight ass with money. Never wanted to spend money, celebrate holidays or birthdays for me or the kids. (Unless it was for his family) anyway I decided that we could come to an agreement and settle out of court on how much money he plans to give me and our kids. I talked to several attorneys and they had told us both how much the court would require him to pay me (according to his pay stubs and taxes) which is by far more than what he wants to give me. He started making me feel guilty and telling me if he gives X amount of money he won't be able to survive because most of his check will be going to me. So me being the nice person that I am I agreed to the amount he wants to give me. Now he stopped working as much and stopped doing overtime because he wants to show the judge that he can't give me as much money because theirs not much work and overtime dried up which is a lie. He's also theatening me to take on 50/50 custody or full custody if I try and ask for more money to the judge. I feel like he's being very selfish. I helped him build his career and become who he is today. I didn't finish my college because he didn't support me and I also didn't work because he wanted me home. I don't have anything. I'm starting from scratch. Everyone tells me I've been nice for to long and he's screwing me over in the process.