Good for you. You are very clear on this issue. I think Steve betrayed you as well, but you are more willing to let him off the hook -- that's a problem. Let's call him a Putz, with a capital "P."
What occurred with Sarah, while painful, is also a clear example of a BOUNDARY. You are capable of them... even though what seems to be a black and white issue you might claim as an 'easy' one. In this instance, you refused to be a 'victim' with Sarah. You cut her out of your life. Period. Friends don't do that to friends. Period. No ifs ands or buts. Period. Non-negotiable item. Period. Got it? Yep. That's a boundary.
Do the same thing with your X.... if not tolerating verbal abuse is a non-negotiable for you. (If it isn't we really need to examine why.) Think of how you were with Sarah when you found out. Get in that frame of mind every time your X goes into verbal abuse mode. Think of opposing council breaking some court rule... do you sit there and take it? Is that in the best interest of your case/client? Would you ever, ever, ever allow it? No. You would probably act/object before it was a conscious thought.
Same thing with a boundary. You just have to be clear on what they are -- make a conscious decision about them -- so that you are very clear when they have been violated.
Does that make sense?
And personal boundaries... when one has to defend them, are usually pretty painful. Lots of people would rather have their boundaries violated than to have to experience pain...
See how good you are at this and you didn't even realize it?
What becomes murkier for you, I believe, are the boundaries you set with men. I'm sure this is because of issues with your father. Girls need to be loved by their daddies, and when that is absent, we become doormats when we shouldn't, or we become overly controlling... we tend to operate in extremes because we never really had that oh so important foundation from our Papas.
So. Say it with me. Steve was a PRICK, a dishonest, dishonorable schmuck who DID NOT deserve you. You did not betray him or yourself because you said you would love him forever, and now do not. To continue to love him would continue your victimization from him. Getting over him was the healthiest thing you could have done for yourself. If you beat yourself up for it one iota of a second longer... your evil internal victimizer is winning. And we cannot allow that.
Does this make sense?
Are you beginning to see that you are NOT a failure as a woman -- you just don't have your self-confidence firmly in place, nor are you clear on your boundaries... this creates CONFUSION. How can you defend your line when you don't know where it is?
Which brings us to 'love.' In your world, as a child, to be loved meant there WERE NO boundaries. None. They got violated all over the flippin' place. So when 'love' enters the picture... you are like a little boat getting tossed around at sea. You do not know what it is like to experience love with appropriate boundaries. No wonder why you are confused. Who the fck wouldn't be?
