What would you do if you had a boyfriend who has 3 kids and ask you to have his kid then 2 days later goes to jail for rape but didn't really rape anyone the girl lyied so her parents wouldnt deny her?

Don't have his child! He can not help you support it and now he is labeled a rapist/pedophile (depends if he's in for rape or statutory rape). And I bet he told you the girl lied which means you have only heard one side. This guy is bad news so find a good one and leave this one. It's really easy to be in his shoes and ask a woman to have his child. You are the one being stuck with it. If he's had sex with a minor he is clearly not a responsible adult and should not have kids.