I am glad it worked out for you. Very often it doesn't so that explains some of the discouraging advice. It was well meant. But NOBODY can give you THE GREAT answer, you know. Just something to fuel your thinking. To help you see all the sides. Don't forget that people give advice according to their own experience. It can be misleading. One should always try to point out the contradictions, the fishy things without drawing conclusions, even if it is very very hard.
I will never condemn you for wanted a married guy. If he got interested in you, his relationship was over, so it is better for everybody. In the long run.
His wife seems indeed desperate. That is normal. She may think you caused her ruin, so you owe her support now. That is very human and OK.
It happened to me once with a colleague. Her husband was unfaithful to her with me but only on a platonic level. Actually that is not different for her. Unfaithful is unfaithful.
She kept me hours on the phone even though she suspected me to have an affair with her husband. I went along because I sensed her dispair. I felt really glad for her when after the divorce she sounded happy on the phone. The guy is on a "I-want-to-stay-single-trip" now which suits me just fine coz I am not interested anymore.
Don't feel guilty but you may feel sorry for her.
I hope you will very happy with the man you chose.