My marriage is falling apart and I want to give it my all before I give up?

We used to be happy. But since I got pregnant with out now 6 week old son the relationship has steadily gone down hill. All we do is fight. He comes home after being gone for a week for work and doesnt even say hi to me for 30 minutes. He is always finding excuses to be gone and breaking plans. He even told me once that he was in another state but then I saw him in town with his dad. I caught him making plans with a girl via text message and said she lives in another state but the phone number was in this state. I know of 2 other women he cheated on me with without a doubt. I know he didnt follow through with those plans with that particular girl because I was with him that weekend. However, I dont know that he didnt reschedule with her. We don't make love anymore and when we do he always seems to be unintersted and in a hurry to be done. If its this bad now is it even worth the effort to try to fix it. What can I do? Where can I get help without paying for marriage counseling?