I think the harshest thing in this is her telling you not to contact you again with no explanation. There must be a reason, whether that reason is "fair" or not and given the length of your friendship she should have been decent enough to explain it. That she didn't is cruel, imo.
I sort of ended a friendship last year. There had been problems for years, but I made the decision during those years that she was who she was and I would accept that the downsides were fine, I just wouldn't expect certain things for her, because after all none of us are perfect. She was funny to be with, we had fun when we got together so the fact that when I was seriously ill she didn't visit me nor contact me to see if I was doing okay was just her and it was sort of fine. Obviously it wasn't really, but at the time of my serious illness I became quite Pollyanna like (they called me that in the hospital), mostly because I was brain damaged and became a nicer person because of it! Anyway! last year she said something about a mutual friend's partner. Someone asked her on social media what was friend up to these days and she replied "She's married to a c*t." Mutual friend saw it - it was in an open group - and was hugely upset." Mutual friend has been my rock and I hers and I was pretty much enraged. So, I first took the cowards way of unfriending her on Facebook, and then she got in contact with me and so I explained to her that it was the c*t thing that had been the reason - didn't explain the rest because I didn't want to throw a whole load of accusations at her,it would have been unfair. It was a calm discussion, I told her I would always care about her, but I didn't think our friendship could go on. She apologised profusely for what she had said about friend's husband and we left it there. There was regret, but no nastiness, because we'd been friends for so long, nastiness would have been wrong.
So, long story short and no more me, me, me. The "break up" of a friendship hurts a lot, often those friendships have lasted longer than relationships with men/partners/husbands/wives,so we feel the loss of them deeply, but there are always reasons and if you are the one ending the friendship then it is on you to let the other person know why. So, I feel for you. There are reasons, there always are, but to just cut you off without having the decency to explain to you why your friendship has reached its end is cruel and so, your DH is right, you really are better off without someone who would be so cruel.