Whether to tell the EX of my current wife about her Bulimia

Is your wife a good mother?

If she is, leave that relationship alone.

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If you are unable to stay in the marital relationship, leave - and stay out of her relationship with her child and her ex. What happens with future partners is truly none of your business.

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The child is three years old. Do you know if the bulimia started before or after the pregnancy? do you have any sort of parental role with the child? do you attend appointments with the paediatrician?

Because you said....I have verified that my wife was bulimic before my marriage/courtship started with her."

You stated you have have a lot of extensive therapy. Based on your about face with the sudden insults to someone here who was just going by what you said, it seems like you need a lot more therapy.

I think you have more than an ethical problem, chai is correct, you need more therapy, and you need to figure out why you lash out at people trying to help you. Many people are dealing with problems you can't even imagine, don't be so quick to toss around obtuse, it's unbecoming.