Friend wants to renew our friendship

Many years ago I had a good friend, well at the time I thought she was a good friend. We were friends for years and had a lot in common. We were similar age, both were single parents with one child, lived on the same estate, went out together, shopped together, confided in each other..

She became ill , me being the good friend, did her shopping, did her washing, cleaned her house, made meals etc. When she got better she rewarded me by taking another of her friends away on a weekend, to thank her for helping her when she was ill. This other woman had popped down to see her twice and that was it.

That hurt me so much. I gradually tapered off the friendship and moved off that estate. We did bump into each other now and again over the years, had a natter and a laugh.

Now she keeps contacting me, tbh, I can't be doing with it, if I wasn't good enough then, well I'm not good enough now. Incidentally, I'm going through a similar thing with my cousin too. I mean why do people treat others badly and then think that they can pick up as though nothing had changed?