If spending time with her is bringing you down, you need to put some distance between the two of you. It doesn't have to be permanent, although I have finally, after 50 years, ended a friendship. Just as Bluebird243 described above, my former friend was always right, hyper critical of everyone including members of my family, and constantly challenging my opinions e.g. about politics, education, music, or whatever. I realised why members of her family had cut ties with her over the years.
I've no doubt I've changed too and become less and less tolerant, maybe took things to heart more, but the strain of treading on eggshells, or simply having to constantly let things wash over me, finally took it's toll.
I simply said it was time to say goodbye. Everyone has noticed how much happier I am without the constant criticism. I know it was the best for me, but it's a hard decision and I understand how hard it is for you.