What to do with his life now? How to integrate into the real world without killing all humans

It's ok to feel bad about shooting William even after all he did. It's okay to be mad at him too.

not ok to kick him in the balls

It is possible to live without William. After he is gone, the world will continue to spin and you will be fine. You are capable and do not need him to tell you what to do.

lawrence

You need to let your daughter and wife make their own decisions like you are now; sure they seem happy not knowing the truth but it wouldn't be fair.