it's too bad you had an unpleasant experience; but men (and women) can lie to you/about you/dump you, on the mat or off. If you have indeed moved on, then don't worry about who he is interested in/living with,pending children, or what he thinks about your past relationship. If you are still tied to him, then perhaps that is a place for you to work on as well.
I think (kid's classes aside, a WHOLE other issue) that we are all adults, and i don't care who is involved with whom. I have had instructors make passes, i'm a big girl and know how to say 'no thanks'. And there have been instructors i've thought were great and would have liked to know off the mat, but old fashioned feelings about asking men out, as much as hesitency over our instructor-student relationship, held me back. I train seven days a week, so do some instructors, especially in small dojos; sometimes when that's all you meet...
i envy folks who train with their significant others...at least no arguements over 'how many nights are you going to that dojo, anyway'...and yet they also have someone they can share time with off the mat. Singles who train a lot give up a relationship, those in relationships often give up dojo time. Nice to get both
I know when i've dated men who don't do martial arts they are not thrilled that i do, and hate the time that i put in. So i say, give the instructors a break.