It isn't a negative post at all imo. You are looking to end a friendship which is no longer working for you as kindly and respectfully as possible.

There are a few different ways you can do this.

1) Slow fade. You gradually reduce time spent together and don't get back to her as quickly as previously. Eventually you fade out of each other's lives.

2) You talk to her about it directly. However this runs the risk of being confrontational especially if the person is prone to this. If talking directly it's best not to apportion blame but to talk about how your lives have changed and the friendship no longer working for you both whilst thanking her for the good times you have shared.

It is a sad situation to cope with. It's possible even if you end the friendship respectfully you may still need to grieve for the loss of this connection so be gentle with yourself as much as your friend is my advice.

Take care and hope you can work out a way that works for you.