Let's put the "terrible person & no self-esteem" schtick on hold for a moment & cut to the chase.
Why are you hung up on a man who "fell" in with you while married to someone else?
What good is it doing you, chasing after a man you have to trick into revealing his lie to you?
How is playing the 'Pick-Me Dance' going to add to your happiness?
www.chumplady.com/2012/04/the-humiliating-dance-of-pick-me/
Have a think about those questions.
If the answer is "because I have low self-esteem" - you are fooling yourself. Worse than that, you are lowering yourself into accepting a second-best life of miserable worry which will ... yup, spiral your self-esteem ever further downward.
So if you can't come up with any other answer than "low self-esteem", for your own good, can I urge you to book in with an expert therapist, & get that seen to? Because it's really not a good enough excuse.
And that's not even from the predictable moral standpoint that you are gonna get blasted with on here.
It's from the standpoint of why the fuck are you consciously allowing yourself to shoot yourself & your life chances in the foot?
Your behaviour around this married man is actively reducing your already low sense of self worth, stopping you from working on your issues with expert help, & blocking you from meeting someone single. Someone decent. Someone who doesn't get off on your humiliation as you Pick-Me Dance for his entertainment.