Maybe she should call her son and tell him when the party is.
(just kidding.)
Eva's right. Would it have been nice to call you first? Yes. Does she have to? No. The rule is: it's my party and I invite everyone to come, those who can't, we shall miss. In our family, we used to sweat bullets over who could come when till we discovered we weren't getting together at all. Then we stopped consulting and just started inviting.
Eva's right. Make that girlie your best friend. Invite them out for a dinner after the party and ask them to tell you everything that happened.
Be overjoyed at the happiness of it all and thank your daughter in law for being so loving to your son. (not kidding)
Now go and play nice.