I recommend that you get this worked out now while your tempers are relatively cool. The longer this problem drags on, the more personal ego will take over. Adult pride gets in the way of doing what is best for the child.
Children, including teens, are fickle. Young teens are notorious for playing divorced parents against each other. It is not uncommon for a teen to get mad at one parent and announce that she wants to go live with the other parent. This emboldens one parent, in this case your husband, and instills fear and panic in the other - you. When you try to work this out in an emotionally disturbed state, you make bad decisions. You are wise to seek counsel from others who are not personally involved in the matter.
I assume that since you are sharing 50/50 custody that you both find the other partner an acceptable parent… no issues of child abuse or neglect, etc. If that is the case, then here is some advice:
Take a deep breath… nothing is going to happen quickly. Don’t obsess over this. Exercise, eat well, read some non-custody related books, pray and take it easy. If you aren’t healthy mentally then you will say or do stupid things.
Talk to your STBX directly. Some attorneys will encourage you to do all your negotiating through them… naturally, they will charge you for every second of their involvement. Hopefully your ex wasn’t taken by surprise with the child support papers. Hopefully you had already talked with him about your financial concerns and didn’t just hit him out of nowhere. If you did, then his anger at you is probably justified. You are both adults. Work this money matter out.
One point of discussion can be for both of you to use the child support calculator on the main page of www.rosen.com and see where things stand. If you are demanding a lot more than the calculator estimates you should get, then you need to compromise. The same goes for him.
Don’t assume that he is suddenly trying to get full custody of your daughter because you are asking for more money. That is such an offensive position taken by too many women. Most men DO want more time with their children and are very willing to provide for their financial needs. Most men are not “deadbeat” dads trying to evade child support. Give him the benefit of the doubt and assume that he wants what is best for your child, just like you do.
Realize that if you two have had a 50/50 time sharing split so far and your daughter is willing to state to the judge that she wants to live with dad, then it is, at the very least, POSSIBLE that you could end up in the position that most fathers are in: insufficient visitation privileges and a court order to pay the other parent child support. I hope you are thinking through that. YOU could end up being the one paying child support to the other parent in the end.
You can talk you your STBX directly and honestly about your financial concerns. Tell him honestly WHY you need more financial help for your daughter. Brainstorm with him ways to address her needs. Let him feel like he is a part of the solution. He might be very willing to pay more child support if he sees a genuine need. But if your approach is to go straight for the jugular or if you use surprise tactics then you can expect that he will respond to you the same way.
I add my support to the suggestions that stepmother gave to you. You need to have a straight talk with your daughter. You also need to decide that even if your STBX tries to use her as a chess piece in a custody match against you, that you won’t respond in kind. Don’t ever let yourself start using your child as a tool for vengence because she will be the one who gets hurt the most.
I think you are a bright and reasonable person - evidenced partly by your willingness to share custody with your husband. Shared parenting is almost always in the best interest of the child.