I was not angry at Sam for his choiced, he ordered everyone not to tell anyone about the pack. So Jacob was under a blanket order he did not specifically tell him not to talk to her. Jacob had to avoid Bella because Sam was worried he would end up hurting her, the first 6 months-1 year are a dangerious time for a shape shifter because they are so easily angered and can transform like he did to Emily. It nearly killed him to hurt emily and he didn't want Jacob to be hurt like that, Bella to.
The order to kill the baby was not one he made lightly. Remember he got all his info from Jacob's memories. Jacob saw that the Cullens where confused and scared of what the baby might be, they were scared to lose Bella but Jacob could not see that, because of his bias against them. So Sam made a choice on bad information, happens all the time. Even if he had known they where just scared to lose Bella he would have made that same call, a newborn Bella is one thing, 7 other vampires can keep her in check, the baby is a unknown will the baby be a total monster uncontrolable or will it have some humanity in it. What if it escapes while they are trying to keep Bella alive? Its to many risk, I do not think he wanted to kill the Cullens, he would rather he could get past them, but invading their house to kill one of theirs he knew would start a fight so he had to think of that.
I like Sam, he has had a hard life and sometimes leaders have to be the bad guys by making the hard choices that we others could not.
R.I.P - Jacob Black [Died August 2nd, 2008](Page 360, Book 2, Breaking Dawn)