Should I be angry at my in-laws?

My husbands family never invited us to get togethers or parties.When we would come around they acted like we weren't there. Though they all did help us out a few times when we needed it.My husband passed away a few months ago. Since then I haven't spoke to them or visa versa.My husbands birthday is coming up in a couple of weeks and the whole family is coming into town to celebrate.Why are they doing this now?They didn't do it when he was alive. I'm furious because I think that this is wrong.