trying to avoid going outside of my empty relationship. suggestions?

Ok so, I've been with my boyfriend(fiancé) as of now I call him roommate for almost 3years. I went on maternity leave march 2016 since then he's been really distant. I thought since I was home we would have more time to spend together, when we first got together I wasn't working and we were together almost the whole day, watching movies, cooking, cuddling, talking making love etc etc. that was great. We decided we wanted to try for a baby. We announced our pregnancy august 2015 and started a new job November 2015. Now while I was working we still had sex, watched some movies spent quality time. We have 6kids in between the both of us and that was never a problem. I was excited to be on maternity because while the kids were at school we basically had all day to spend with each other. I've had to beg for him to go shopping for baby stuff with me, he never wanted to have sex anymore and watching a movie was me watching the menu screen for 2hours so he can sit on the porch smoke a cig and watch YouTube for hours at a time. I expressed my frustrations and he promised to change. I went back to work July 20 16, since then it's still a struggle. He constantly does the same thing. Sits on the porch all day long, smokes and drinks. Comes in to cook dinner since I have the baby. He'd rather do all the chores if it doesn't involve him taking her. At night he comes in and plays with the other children which pisses me off because that's normally around 930pm and they need to be in bed and so do I have work. For 2hours he's loud and just ignores me when I say I'm tired and need to sleep. Since having the baby we only have had sex twice a month if that and I'm just feeling a lil unwanted. I started talking to someone via fb. He lives out of state and I kind of use that as a excuse to keep messaging him. I'm not even hiding the fact that I'm messaging him. I don't want to have any strong feelings grow for my friend and he knows I'm in a relationship. I'm tired of begging for time and attention from my partner. I took us to paint nite, I offer movie and dinner dates but after to 1 or 2 we are back at the main problem. I feel like if I work and take care of home and you don't you can at least give me what I need.  What should I do.? I told him if you can't give me 24hrs any day of the week how do you plan  on spending the rest of your life with me?