it never matters how long you've known someone

I'm kind of ranting here but also unsure if how I'm feeling is expected. I had this family friend that I have known for 20 years. we grew up together and went through a lot of similar issues with our now estranged mother's. she is four years older than me and has two siblings that are two years older than me and my age but I was always closest with her. through the years our families lost a bit of touch but we connected through social media, college and rejoining our parents old baseball team. since she moved away about two years ago we haven't seen much of each other but still talked now and then. in June I was invited by her sister to her bridal shower but had not yet received any information about her wedding which was in September. well I went to the shower because she was my longest friend and I still cared about her as if she was my own sister. during the shower, it was clear I was invited by accident by her sister, she barely spoke two sentences to me and gave me a half hug when she thanked me for my gift. she took pictures with everyone but me. I felt so hurt the entire time and was just holding back tears. as soon as I left and got in my car I just started balling. since she gave out her wedding invitations two weeks prior at her family BBQ I thought I would have received one at the shower, but I didn't. I still have yet to receive an explanation or even a thank you card for her shower gift. I can honestly say I have never been so hurt by someone who I thought I would always be close with. she invited people to her wedding that are more her parents friends and that she barely talks too. I always thought about inviting her and her whole family to my wedding as they were such a huge part of my life, but seeing as I couldn't even get a thank you I guess I didn't matter that much to her . I was only hoping to be able to celebrate the fact that she had found her true love and was on to this new and exciting chapter in her life.