Ok so im 38 wks pregnant and found out 3 wks ago my bf has bn cheating 4 the last 2 months?

He never has before and says he wants to be with me and she means nothing but i keep finding out he is still seeing her and has not helped at all since i have been pregnant. i have explained to him too many times that i dont care if he wants to be with me i just need to know where he stands with being involved in our sons life and he says he will be there but i still can't get him to even put the crib together for me. he was the one that was so excited before we ever got pregnant about having kids and then he waits till its almost time and does this? I am so totally confused!!!!! please help