Am I better off to just go now, or keep trying to make my marriage work.

My husband and I have only been married 3 years, have one toddler and another on the way. We have been fighting heaps on and off really since I was pregnant with my first child. It seems as though my husband always wants to be the centre of attention and can't handle me having any attention because I'm pregnant. I have been working part time since my son was 4 months old, often pulling in a similar wage to my husband, but since I haven't been working full time my husband expects me to do everything when it comes to looking after the child, plus all housework, dinners, etc. He has only started to bath our son in the past few months on nights when I complain my back is sore from my rapidly growing tummy. He always puts his family and friends first. His mother has been quite rude to me over the past few months, saying nasty things, hanging up on me and now ignoring me if i see her in the street. Of course I tell my husband how she treats me, but then he just defends her and says i should put it behind me. My husband often works long/extra hours without any extra pay and then in his spare time will run to his parents to help them with farmwork. They don't ever show any appreciation for all the work he does for them and as they have a lot of cattle my husband purchased 2 cows to have in their paddock eating with theirs and they now send us a bill for agistment. I am quite often at home on my own which is where my husband likes me to be. If i do make plans to go somewhere on the weekend he usually will make sure he is able to come with me. Otherwise it is very hard to socialise when looking after a small child. If I complain it all just ends up in a big fight, which I don't want for my kids. So am I better off to just end things now before they are old enough to know any better.