Call around to find a family law lawyer who will do a free consultation. Some will do them over the phone. If you can afford it, pay for a legal consult...it's worth every penny. The lawyer I hired cost 140$ per hour...so I forked out that money and she spent well over an hour with me going over ALL the details regarding separation, custody, finances. It was INSANELY helpful and I felt a lot more...sane after that consultation.
I think it's a real good idea to consult a lawyer at this point because you have been the breadwinner. Your AH may be eligible for chid support if he gets any kind of custody.