I'm from Wisconsin and the child's mother. We have joint custody, placement is with me and my ex has generous visitation that we agreed on during our divorce.

Every time there's an increase in child support, he threatens me with some kind of action involving our son. He had hidden income from the state support agency and was caught, due to an audit I requested. His witholding went up by more than $200 per month. Now he has filed the paperwork to change our custody arrangement to one week with me, one week with him.

My son (who's 13) is hysterical about this. His dad remarried a month ago (was with the girlfriend for 5 years before) and he loathes her and doesn't get along well with his dad for the most part either. He's told me repeatedly he'll run away if his dad makes him spend more time there and when he found out about the filing this time, he was so angry he could barely speak.

I've called an attorney - I refuse to go into this process without one - and will most likely have to hock everything I own just to pay the retainer. His advice to me was to wait until I was served and then we'll take it from there.

My question in general is this - I am on permanent disability for 2 things: a rare type of blood cancer and a significant case of bi-polar disorder. I am on medication and it's under control and has never seemed to be an issue for my son. I have regular doctor and therapy visits and I've explained it all to him. My ex obviously knows about it too and is using this as his reason to amend the custody arrangement.

Is this a valid argument if my situation has never been an issue and I am under active and ongoing treatment? Is my son's decline (As and Bs to Bs and Cs) in grades this year a valid argument even if both my ex and I have agreed the problem is the usual coming into puberty distractions? What do I need to start documenting? My ex travels at least a full week out of every month and never asks to make up visitation (I'd let him); he's constantly behind on his child support, not to mention the amount he's hidden from me in the last year.

I guess I'd like an idea of what to expect, how long the process generally takes if we do end up in mediation and that fails and we're sent straight to the judge. My attorney to be said my son would be appointed a guardian ad litum and his feelings about staying with me would be an important part of the judge's decision but I'm terrified that the other things will outweight that.

I can't eat or sleep since my ex told me this and I'm not even sure if I ought to be getting this hysterical yet.