Definitely do not send it. This letter will just reinforce that you are not a threat.
Disclaimer: just my take and humble opinion here. These kinds of situations are tricky and I admittedly do not have first hand experience.
Men who go after married women are "predatory". They may ultimately justify themselves as being "in love" and that they "couldnt help it", but in most cases their own self-interest (pleasure) is overiding any sense of guilt or fear of getting caught or confronted (pain).
Depending on who this person is, he may be a strong personality competing for your W. If you ask for him to consider the damage he is doing, then you are coming from a position of weakness (begging/pleasding), and he will just lose respect for you and assume he is winning the "contest".
If he is a weak personality, he may actually be afraid of confrontation. If you plead with him this way, it will ease his fears of being confronted. Again he will lose respect for you.
In both cases, it will only do harm.
Spellfire aka Mike
"Women do not like controlling men. They respect and are attracted to men who control themselves. They ultimately are repelled by men who allow themselves to be controlled." -S&A
