Hi Clare,
So many of us have done the same thing, and it isn't necessarily the case that you're responding to how other people treat you, but to your own internal dialogue.
So many of us are way more unkind to ourselves than we would even
consider being to an other person!
So give yourself some kind thoughts, stick them all over the house on sticky notes, put them on a cd and play them back to yourself, repeat them while you are exercising, whatever it takes.
And remember, you have a whole world of people on this forum who care about you and who actually get it! we're here when you need us.