41F struggling to let go of a one-sided friendship with 42F

I have had a close friendship for about five years with someone I considered my best friend. We became very close during one of the hardest periods of her life — she was going through a separation, and I stood by her through everything. I was the one who consistently reached out, checked in, listened, and supported her emotionally, even when she rarely initiated contact herself. I told myself that being there for her mattered more than keeping score.

Over time, she healed, found love again, got married, and is now in a happy place. I’ve genuinely been happy for her and continued to show up for her in every phase.

But now I find myself emotionally exhausted.

I’m going through a difficult period in my own life and, for the first time, I really need a friend who shows up for me — someone who checks in, who cares, who is present without me having to ask. Recently I tried calling her because I needed support. She texted saying she was busy and never called back.

That moment hurt more than I expected. It made me realize how alone I feel despite investing so much into this friendship.

What makes this harder is that I’m struggling to let go. My heart aches, but I also don’t even have the energy to explain my feelings to her anymore. Part of me wants to release this friendship quietly, but another part of me is grieving what I thought we had.

Has anyone gone through something similar? How do you let go of someone you care about deeply when the friendship no longer feels mutual?