Dealing with stepmothers?

I have an exhusband, and we have a 5 and 7 yr old. I am remarried and have a 4 mo baby. My ex has a new wife (no kids). I want all of us to be as friendly as possible for the 5 & 7 yr olds sake. I am talkative and try to make conversation with the stepmom. I try to talk about the kids and intitiate conversations so that we can all be a TEAM parent for our kids. I want us to raise them the same so that they have consistency between households. Well, the stepmom pretty much ignores me, refuses to meet, barely says "hi" or "bye"...no eye contact and just keeps talking to a minimal. It is SOO uncomfortable!?!? My ex says that I am reading in to it too much and that the stepwife has no hard feelings. I can clearly feel the tension in the air. But plain & simple: I want to get to know whoever is around my kids or influencing my kids. My husband and my EX get along just fine and there is no uncomfortableness between them. Just her & I. Unfortunately. My kids notice it too. Opinions?