This really isn't enough information. Is he right, that the arguing between the two of you has been unbearable, and is not typical of how your relationship was before you got pregnant? If so, this might be fixable. Sometimes pregnant women's hormones make it very very difficult for their partners to tolerate.
But if it's him causing the arguments, and he's the kind of guy who leaves when he gets bored and doesn't take responsibility for his children (you are the second mother of a child for him, so this is likely the case) then it's less fixable.
I'm not clear on if he is asking you to leave the house where you both live or if you are somewhere else, such as at your family's house, and he is asking you to leave there. Also, when you say "with my boyfriend's second baby," do you mean someone else is the mother of the first baby? Finally, does your user name mean you are 15 and he is 17?