"Anyfucker,( ...) maybe breaking up the family home, maybe letting her kill herself, directly or slowly is the manly thing to do, " It is SHE doing all this, not YOU. You dont have to stand for her shitting on not just you, but your family.
I agree you have to assert yourself, and I agree with SGBs advice below that you are very unappealing when you turn yourself into a victim, there is nothing sexy about a weak man. Sadly when it comes to the sexual force (not the verb, the noun) women mostly like strong men, not limp biscuits with pleading puppy eyes. Turn yourself from puppy to wolf! Let her see the strong you. Get on with your life.
Accept that the relationship, if not over, at least is changed. Tell her you wont put up with sharing her with other men, tell her you are prepared to divorce her on adulterous grounds, tell her you will see a lawyer (and do). Whether she choses to kill herself over it, is her business, but you wont let her blackmail you.
In my experience, (and believe me, both myself and friends have experienced men threatening to kill themselves when faced with a breakup it is quite common) the person who comes out with the "I am gonna kill myself if you break up with me" isnt actually planning to kill her/himself, but only looking for another way to exercise control and get his/her cake stall to eat. It is the last straw. That, and "oh my mum is dying, you cant leave me now" which is another one....
You may not go through with it, but let her THINK it, for now.
Grow balls.
The look, the body, it matters less than the sexual force in the man, as perceived by a woman.
And to share a little personal trivia. When I look at my husband and start pondering bed time action, it is not his face, not his body that set me off, it is the potential it is the masculine and sexual force that inhibits him, that I want... So it does not matter so much how good lover you are, what you look like, whether your body is well toned or not (female sexuality is a little different from the male ] ) it is your masculinity, your sexual force, your strenght.... (not talking physical strenght)
So, take charge.