Posters here can claim they are only attracted to heterosexual men all they want. It's a lie
No, it's really not. You are a bi-sexual woman, with a bi-sexual partner. You don't get to decide for heterosexual women, what they want. The thought of my DH finding men attractive, actually turns my stomach. That does not make me a bigot. In fact you are the only one name-calling.
funny how no one talks about straight women 'craving cock'
Of course straight women crave cock. Not a very nice way of putting it, but I can assure you that they do. 
Your lesbian friend probably is biphobic. It's a massive issue in the gay community. Gay men are also shitty about bi men
I suspect because they are savvy enough to realise, that no matter how great they are in the bedroom, there will always be a sexual desire in their Partner, that they cannot fulfill. That is unnerving, no matter what that desire was. It could be dressing up as a barn animal, if you aren't prepared to do it.
But if you blanket reject the idea of a relationship with a specific group for reasons which have nothing to do with your relationship and are entirely to do with your preconceptions, that's probably prejudice
So what? I would never date a Chinese man. Because I don't find that race attractive. So shoot me. and they are too short
And my lesbian friend has experienced heartbreak in the past when bisexual women she has dated have ended up choosing a man to settle down and have kids with. She has decided to rule them out as future partners which is absolutely her right
I would have done the same, I can totally understand why she would do that.
speckledduck You're missing the point spectacularly, though. You're equating his bisexuality to his cheating, but they're two entirely separate things
I disagree. He chose to cheat specifically with men. Of course speckledduck will consider his bi-sexuality to have fuelled these extra marital encounters. He needed something he couldn't get at home. If he had been openly Bi, and had had many relationships with men before, and then settled down, maybe he wouldn't have ever strayed. But this was a pandora's box for him, that had never been opened. Mid-life crises are bad enough, but I would imagine they are even more spectacular if there's something like this going on.
His being bisexual does not equate to having a serious effect on your health
Yes it does, if he is going Gay dogging. 
eskimomama and speckledduck 
for you. You sound like really strong women and you don't have to settle for this.
Not the same, but I found out 15 years into my first marriage that my "D"H was a serial cheat. He'd tried to get into the pants of every female in my life. No-one told me. Well, eventually someone did. The horror of this, the embarrassment was awful. He'd (roughly) slept with 10 other women, one was my best friend. She was my counsel, whilst shagging him. It took me 4 years to get my arse out of there. It's so hard, as it's your whole life you are re-evaluating.
Anyway, I've got a lovely DH now. My point is, you can and should move on from these men, and in time, find someone else. Baby steps, work out the money, the logistics, line all your ducks up etc.
There are billions of men on this planet. These ones aren't right for you.