I really can't stand my husband....?

we have had problems for years now. I have stayed with him after numerous betrayals that seriously have effected my general happiness about life. He leaves at 7 am comes home at 8 or 9 every night, is always late,ect. I made a pro /con list last night and have 3 pros &17 cons. We have 2 children I have expressed to him numerous times what I need from him and he says he gets it,but never sees anything thru. why am I finding it hard to just walk away? I have common sense and I don't understand what it will take for me to go to a lawyer. Does anyone else feel this way? If you are divorced how long did it take you to actual go thru with it ?