Best friend breakup?

Hi - looking for some advice / comfort. My best friend of 30 years suddenly acted strange once I had my second child. Didn’t come to see me, didn’t seem to really care. She doesn’t have kids of her own, and is just forming a new relationship. Then she cancelled on something really important to me right before it was supposed to start, which is unlike her as she’s always supported me. We had an argument, which in my 30 years has never happened. Since then, she’s pretty much put me on the back burner. I emailed her several months ago about my feelings as it’s been weighing on me. We finally met up and she told me that the email made her even more and never responded as hoped it would just blow over. Fast forward 1 year since the original argument, it’s never been the same. I think about it every day and beat myself up over it. I’ve spoken to my counsellor and she said to try and let it go and not to think about it, keep my mind preoccupied. That’s hard. This is hard. Anyone had a similar experience?