A long standing friend of 15 years has behaved pretty badly towards me.
We have had a good, solid friendship for years, over this time each being there for the other, and generally a very decent lovely relationship with lots of shared memories.
For the last few years though something shifted, she continues to come to my house for drinks, lunches, dinner, parties etc but then stopped inviting me to hers. Fair enough. I don't invite friends over to be invited back. After a while though I found out from other friends that she is in fact having lots of dinners etc and she just isn't inviting me, which wouldn't be so bad but she is always telling me (lying to me) that her birthdays are low key this year and she isn't doing anything etc. She is a bit of a networker so I found it hard to believe even at the time. I was really quite hurt, as we have celebrated our birthdays etc together for ten years or more. I let it go, after all it is up to her who she invites.
Fast forward and I had a milestone birthday in lockdown and invited a whole group of great friends to my house for a celebration last weekend. The date was sent out two months in advance, and everyone accepted. It took a long time to organise dinner and drinks, table etc for thirty people and she knows how much work it is to organise these things.
Four days before the dinner she cancelled stating she had something else on, it turned out to be a pizza night with another family. I was obviously really hurt and insulted and told her so. I think it is rude and poor form to cancel a prior fixed arrangement, particularly for a kids pizza night. My friend told me her dd was screaming to go and wouldn't take no for answer, so she felt she had no choice but to go 
At this point I discussed the fact I felt our friendship had become uneven over the years, that I seem to be doing all the heavy lifting and I am not keen on continuing as we are. I genuinely can't see the point, and it is making me feel utterly shit, used and abused, and friendships shouldn't feel like this. I have better friends that do not treat me like this.
Now she is inundating me with whatsapp messages telling me that she does care, and that she hasn't had that many lunches or dinners and it is me being over sensitive! Now she has taken to just pretending none of this ever happened, all the while refusing to accept she has hurt me or even apologise for letting me down on my 40th birthday.
I am confused, if she wanted to move on and spend time with other people fair enough, but I don't think that is the case as she messages me now every single day. Yet she seems totally unwilling to actually nurture our friendship, and does not seem to have very much respect for me anymore. To cancel a special occasion at such short notice for a shoddy reason is really unkind. I think she enjoys coming to my house, hanging out with lots of friends and new people etc, but seems to feel entitled to do this without reciprocating.
I think I should let the friendship go? What do you think? What would you do?