@LAS504
First of all, I am sorry that you had to have this experience. I guess I am wondering why you wanted to spend your 40th Birthday at a beach house on your own with your best friend without the involvement of your husband or other family members?
You call this girl your best friend but did you both not talk about the set-up of the weekend before you all arrived? If it were me, I would have discussed in detail the plans with a said friend before the weekend and then that would be the opportunity for her to tell me that my friends are coming and then you can be like okay I will invite people as well.
Even though it is incredibly rude of the way everything went down for you, these people (from what you say) do not know you, and we don't know what has been reported to them before the weekend. Your friend could have played down that it's your birthday or just forgot to mention you altogether. We will never know!
I also think you have to take ownership to a certain extent. You knew that she was inviting people (from what you said, you knew others were going to be there whether it went down the way it did or not) and you had the opportunity to include your people so they can give you speeches and do something for you, but you did not invite your husband, family, other friends? Why?
My friends are important, but my husband is my whole world so I find it hard to understand why anyone would want to spend such a milestone occasion without that person (unless there's backstory I do not know about then I am sorry).
Going forward I think what's done is done and you cannot change the past, you cannot control the behaviour or actions of other people. All you can do is control what you say and do. I am not saying be friends with the girl again or for you to move past it and for everything to go back to normal but you could sit down with her and have it out peacefully and constructively way to show your friend that you were hurt. I think choosing to forgive someone is not about them, but it is about letting yourself free of the situation and the emotions and baggage that comes with it.
You are clearly still hurt, or you would not be writing something on an internet website about something that happened a year ago. I remember last year my friends annoying me at times, but today I cannot remember why so it must have really struck a chord with you, and I do not think you have really processed this experience. You also most likely feel like your 40th Birthday was ruined and I do not blame you, but honey give yourself a do-over, it's not too late.
Go big or go home and for your next birthday, organise the biggest best party, invite everything you know and love and do a theme like If I could be 40 again, this is what kind of party I would have or something. This idea sounds better in my head also. Whatever you do, just let go and move on. You are worth more than this and whether your friend intentionally made it all about her or not, what's done is done and focus on your family.
I had the one best friend since high school and this past year because her life went a different direction, that friendship changed. I am a sad yes, but the way I see it is this. I am okay with whatever happens as long as I have my husband, he is my everything, and it is only HIM and HIM alone that can disappoint me so much and make me cry. No one else gets that satisfaction.
I hope and pray; you feel better soon, no matter the outcome. Sending you hugs and well wishes to you and your family. My only last piece of advice is that if you want to respond to your friend (if you have not done so already), be polite about it. If you do not want to see her, then tell her your busy and will get in touch with her when you are free.
Best wishes and I hope you start planning that party because you really do deserve it.