I don't know where you live, or what the laws are there. Here in CO, it's not that hard for a Dad to get 50/50 custody. But, if the Dad lives in a tiny apartment, or doesn't have a car, or works 100 hours a week, or has never changed a diaper, that argues to at least START with him having less parenting time than Mom, who has always been the primary caretaker. I am sure your L will talk about this stuff with you, but just wanted to throw that out there.
As for him not knowing how to take care of kids, do you mean he is a danger to them, or he just won't do it the way you would, or to your standards? I have had to accept that he does not parent the way I would want him to, but my kids will probably survive. What kind of R they will have with him, I don't know, but I can't be in control of that. And neither can you. So as long as you think he will keep them safe, you need to get past the idea that he can't take care of them, because you are only driving yourself crazy.
me: 44 XH: 42 M 11 years D10 and S8 Bomb drop 9/27/13 D final 7/1/14