Can i file married fiiling jointly?

my ex is taking to long an playing around with her W-2"s.we are in the process of getting a divorce.im paying child support for our child that we have together.she has another one by another guy. i want to file my taxes now because have school that i have to pay for.i know that because we were married last year i have to file married filing jointly/seperately. she told me that i cant claim our son because she needs the money.if i dont claim him then i am goin to owe because i have him on my tax forms at my job. my question is if i go ahead an file as marred filing jointly can she file her w-2 later after me?