I don't know what your marriage was like before, but, in my opinion, any man who asks his wife for a divorce AFTER SHE JUST HAD A BABY SIX WEEKS AGO is not really entitled to having you worry about his feelings. Be classy, don't be nasty, take the high road, but do what you need to do to take care of yourself. And if that means being with your family -- well, being separated from the baby is one of the consequences of the choice he is making. Sure, you're going to revisit the situation later when your daughter is older and needs more of a relationship with him -- but any man who would even CONSIDER suing for custody of a 6-week-old (unless the mom was a danger) is not someone whose feelings deserve a lot of your attention.
I EMPHATICALLY agree with all of the posters who advised you to get an attorney ASAP. You are still postpartum, for God's sake, and you need someone who is looking out for your interests. There is no way you could possibly see things clearly or objectively with all of those hormones still swirling around, not to mention the lack of sleep. It wouldn't be a bad idea to see a counselor ASAP, either, to help you sort it all out and see what you're dealing with.
I would especially check with the attorney before you do anything like move money or move out of state. Be sure you are doing things the way you are "supposed" to so it doesn't look bad for you later.
You WILL get through this. And you and your daughter will be fine. Best of luck to you!!