I had a threesome after my relationship ended

A year ago, threesome is something that I deemed as a sin.Swinger couples and singles are people who I kook down upon. But now, I am one of them. All of these happened over one night and I turned from a clean and pure orthodox to a swinger.
It all started from my bf broke up with me for me not wanting to have a threesome with him and a stranger. I thought having threesome is sinful. It is a disobey of my belief. I refused to do that even though he threaten to breakup with me. But I ended up having threesome with a couple who I do not know before after I was drunk! How ironic!