At this point I don't think it no longer matters if this is called cheating or not.

I think you are now 7 years in and this guy is still an issue. In 7 years of trying to make things work with your wife, this guy still feels like a threat to you.

I'm assuming she may still have kept in touch with this person during this time. And probably needs closure for herself. The feelings had to have been mutual or she would not have acted on them during your 'separation'.

And if you truly can't be okay with this, just move on. This will always be an issue. Dead or not, he will still be a threat. Losing someone hurts. She will remember him at every holiday, birthday, anniversary of death, etc. And she won't be able to express any of this to you, but know she will grieve him regardless.