Should i claim my kids on my income tax?

Me and my kids father is not doing good right now! I'm pregnant and have 2 kids by him!! For the past couple of months he's hardly had time for my kids!! He gets them 1 day out the week and even will still try to get out of watching them!! Well he has loans that need to be paid off!! We usually file jointly!! With his unpaid loans we gotta get an extenion from the irs and won't be able to file till may!! My question is should I just file alone and claim both my kids?? He's so disrespectful and hangs up or never answers when I need to talk to him!!! Can I say again we have another baby on the way!! He's unsupportive I know I will be raising my kids alone!!!