I'm still very new here but I remember that feeling in the pit of your stomach like it was just yesterday, the anxiety was HORRIBLE.
For me it got better when I took all the necessary steps to protect myself, my kids and put myself in a situation where the only thing left was the emotional anxiety. Let's be honest, many of us wives or girlfriends or husbands/boyfriends anxiety is not just related to emotions but to finances.. My xhb blew threw our life savings, my kids college funds in addition to bringing each of us to our knees emotionaly. Once I took the necessary steps to protect myself fianancially I then gained the self-esteem and confidence I needed to focus my emotional energy on myself. It was by far NOT easy but with a lot of effort I just started doing MORE things for myself and less things for him.
And another thing... This is not to say men don't have this, but MOST of us women have a very keen sense of intuition. Do not confuse Intuition and that GUT feeling something is off, with anxiety over IF he will or not. MOST often that knot in my stomach was my gut saying.. It aint over! So that was another thing I had to learn. I sometimes pushed that gut feeling off and gave him the benefit of the doubt only to be knocked down again, once I really learned to listen to my gut and what it was saying.. I was no longer confused. Years ago I had an Al-Anon Sponsor who taught me that. I didn't stay in Al-anon long, but I got a lot from my then sponsor who really taught me to trust myself first.