Grounds for dismissal or am I being Petty?

I am a married woman we both are almost 40. My husband leaves the house 5 to 10 times each day making runs and it is wearing me out mentally wondering what he is doing out there. Yes we both work so imagine this leaves less than 8 hours in a day to make said runs. He even leaves at night while I am sleeping sometimes I wake up and he is gone. When he comes back he says he went to get food. Doesn't matter if we cooked or not. He always has a reason to leave the house. I am ready to end it over this amongst other things I think he is seeing someone else and he is mentally abusive with this behavior as well as always bringing up things that happened in our past that we were supposed to have moved on from. I feel like he takes advantage of the fact that we have a young child at home and so I can't make moved the way he does.. thoughts? Anyone been through this before?

RESPONSE: I have spoken with him about this numerous times and I'm done. We are on our 2nd go round and now I am at the point where I want to be able to have him come home to an empty house. I should add that he smokes marijuana so he uses that as an excuse half the time....that he is going out to smoke then them he takes off in the car. He was dying to get a new car and now he is gone twice as much sinxe he got it . The other half he says he is doing things for us or his family/mom/grandmom. To the young lady that says she is the other woman and pregnant how often does he see you?