Can dad get full custody?

Andrea • Due Dec 14th ❄ but baby came 11/15! 😍
I live in NH currently with my babies father. Lately he's been more aggravated and says a lot of hurtful things. He told me then other day that he was going to leave and he was going to get full custody to which I said good luck. I used to be a self harmer, NOT anymore. He seems to think that he could win the court over by somehow proving I'm crazy. Is this possible?