Would You Trust him?

I think it is important for children to have their father in their lives but if me and my partner continue down the path we are on right now we will split up and i worry about him being alone with my two kids. i have a 20month old and a 7 month old daughter, he has never done anything for them from the day they were born no dirty nappies, never has he gotten up in the middle of the night and apart from playing with them for 5 minutes a day he doesnt ever want to spend any time with them. he has told me if we split up he wants them every weekend over night and it worries me because he drinks quite heavily and i dont want my children to be left alone with him when he drunk and he has a very short temper if they wake him up at night i am worried he will hurt them, he has yelled at me before when both of them have been cryin at night and i couldnt keep them quiet, should i trust him with my kids or should i make him take me to court, if i did go to court would he get custody any way?