Yes, more than once.
When I was 20, with my then boss. He was the life and soul of the party and a serial cheater (no kids), but we had a full blown affair and he left his wife after 10 months and married me as soon as a very quick divorce came through. We had DS (now 22), and divorced after 12 years. He was 8 years older than me and it began to show and we just weren't compatible any more. He and DS still have a great relationship. I don't regret the affair or the marriage, but now I'm older and wiser I do feel some guilt.
Then when I was 33, with a man I met on a dating site. He had 2 children. He left his wife after about a year. I'm pretty sure his wife was already seeing someone else as the children were introduced to her new "friend" a week later, and she went on to marry him fairly quickly. For that reason, I don't feel too much guilt, although I was always painted as the baddie where the children were concerned, and they never really liked me. We got married after about 5 years and that lasted 4 years. he turned into a violent, abusive prick, so I guess I got my just rewards! I regret ever meeting him, having him associated with my DS, and ever being persuaded to marry him (I didn't want to, and did so to shut him up). I honestly don't know what I ever, ever saw in him. I think sometimes, and hope it's not, that I had/have such low self esteem that I was thrilled that I could "steal" a man from his wife.
While that last marriage was in its final throes, I started seeing someone else and saw the light, and kicked violent, abusive prick to the kerb. He spent a few months badmouthing me to my family and our mutual friends, neglecting to mention that he beat me up regularly. He then did a bit of Tindering, was unsuccessful, and then met a woman he is now living with and due to marry next year. I feel very sorry for her.
I'm now living with DP, who tuts disapprovingly at me for having been OW, ignoring the irony that he was, actually for a couple of months, OM!
I've probably, unwittingly, also been OW on ONSs, in my less stable days, inbetween relationships.
All in all, I'm not at all proud of being OW, don't tell other people about it, and am sad for the hurt I must have caused 1st wife, and for the children of the 2nd wife, although their Dad was never a good Dad to them, even before I came along.