Tbh I am a friend who drifted away or didn’t put as much effort into a friendship. There are valid reasons and petty excuses alike, but as the one who drifted away I have to say that your friend’s complaining is ridiculous. I’m sure she has her reasons for drifting, but ultimately she is the one who failed to reciprocate the friendship. If she wants to sit down and have a calm discussion about it and you want to salvage the friendship, then by all means go for it! But if she isn’t willing to meet you half way, then stepping back is definitely the way to go. You need to take care of yourself.