What should I do about my best friend? This is long but pls read?

My best friend and I got into a huge fight last month. Let me first start off by saying I am 28 and she is 25 and we have been best friends for 6 years now. We did everything together. I am engaged in a happy relationship for 6 years now and she is living w/ her boyfriend of 10 years and she is 5 months pregnant now. Well, last month I emailed her telling her that on Saturday I was going to the beach finally for the first time this summer. She replied that Saturday was the day her and her sister were going to do her baby registry and she can not believe that I forgot. Now, let me say that she made plans w/ her sister to go 2 months ago and said I can come along if i wanted to. I told her I would love to come. I really just forgot the day since it was 2 months before we were going. So I told her that I would not go to the beach and I would be there to do the registry w/ her and that I was sorry I forgot the day. She replied back that she no longer wants me to come because I am a horrible friend since I forgot the day and that she also does not want me to plan her baby shower anymore and all the money I spent so far she would refund to me. She said she would invite me now only as a guest if I wish to attend and she said I will see you there if you can remember to show up. Well she goes on about how I am a crappy friend and all this rude stuff. So from there is got ugly, I told her that I was sorry I forgot but I have every intention of still going and that as long as I was going to go I dont understand the big deal. (Mind you I have had alot going on w/ my brother having a baby to and I was having some health concerns at the time) She cursed me out and said not to call or email her anymore and that she has no time to waste on people like me. I responded to her that I do not understand why when we get into a fight she has to say mean things to hurt me. I told her htat I do not do that to her and I would appreciate her not doing it to me. Well, she called me at work and told me to go F*** myself and that she never wants to talk to me again. She is the type of person that thinks she can be rude to you and if you answer her back you have no right to.She is very stubborn and even if she is wrong she will not apologize or admit she made a mistake. Well basically we have not talked since that day and I have been very upset over the entire thing. I was always there for her whenever she needed me and I always had her back. Was I really so wrong here that I deserved this? Or do you feel she over reacted on the whole thing? Should I call her or should I just forget her? Pls help! Thank you!