Mother-in-law Hell

Hopefully you can help me before this destroys our marriage. My husband and I have been married for 4 years and together for 5. Right now we live with his dad,cause we cant afford our own place.His dad is home mostly on the weekends cause he drives semi.When he gets home our lives change instantly.He talks about the same thing over and over again(like a parrot),very forgetful,wants my husband to do things for him that we cant afford to knock off the rent $ we owe,harps on me about going to church(I was not raised around chruch,and have no interest in it),there is so much more.Now his mother want my husband to constantly go over there and do house work all the time,knowing me and his 2 very young kids need him here at home,always calls for the stupidest things.Like I said there is alot more that drives the both of us nuts.Iam afraid this is gonna ruin our marriage and our kids.O and another thing his dad does not listen to me about how i raise my son, he gives/sneeks him junk food when I tell him not to then gets mad and says that we dont trust him with our son.I tell him you ask me if my son can have something not just do it without asking me.Can you please help me!!!!!!!!!!!!