Ex spouse default Child maintenance and claims mentally illness

Hi i need some help... I am from Singapore. I have 2 children with my ex spouse, it's difficult for me to seek legal advise here in Singapore because it's very expensive.
My ex spouse default his child maintenance for the 3rd time and the previous time he did hire a lawyer. All the while he is fine until the 3rd time I file for arrears he claims he is mentally disable and can't work now. He had went to IMH for reviews and will be getting his mentally report. The way he act like a crazy man is as good as the channel 8 1st lead actor, even the judge sympathisehim. He keep telling the judge not to force him and he will commit suicide.What can I do now and with his mentally report can I file for sole custody and denial access to him?