Oh man! I'm so sorry for her heartlessness.
First of all - you didn't cause these problems. Yes, having CF may have prevented you from 'naturally' fathering children (I say this as you mention 'he' has children, so it sounds like that may have been a significant bump in your relationship). However, there are other ways to be parents - if she refused the adoption or donor IVF methods, then she sounds incredibly selfish to me.
Cheaters will be cheaters and excuse their actions in whatever way makes them feel better about it. My ex was fond of picking up women by telling them how sick his wife was and made me sound on my deathbed for several years. Finally, a few of our friends had enough and came clean to me and so many 'wierd things' that had happened just fell into place. He was a horse's pa-tut, but I still felt like the rug had been pulled out from under me. And this was round 2!!! I forgave and forgot the first time.
Yes, finances are a strain when we are sick. Yes, we need the support of a good friend - spouse is nice, but a good friend is more necessary. She was worried about being alone when you die? Good Lord! Now she can worry about being alone with HIS CHILDREN when he gets hit by a car/has a heart attack/whatever. We are all here for a reason and for an undertermined (to us) length of time. She is using our disease as a crutch for her unfaithfulness. I say good bye and good ridence.
I fully agree with those who are telling you that your best 'revenge' is to take excellant care of yourself and live a good life without her. I was amazed how much good a divorce did do for me. I was able to go onto disability after we split and stayed on that until I felt better. I'm back to work again and have been for several years. I went from being in the hospital every 3-4 months to every 10 -12 months now.
Go out and become involved in something somewhere - tkae a class at a local college, go to church & faith-based socials, clubs, new interest...whatever. Get into counseling for depression and don't be afraid to take some perscription meds to boost you over the blues. You deserve it to fight the good fight and to show her up. Do not allow her to make you feel guility that your disease broke you up. Listen to the tag line you have chosen and ponder that for a while.
In all my mess I had a best friend turn into a lover and now we have lived together for nearly 9 years. He keeps me driven to take care of myself and to learn and expand my horizons. I'm not sure how I would have coped if he hadn't been there, but I came to realize that he'd been there for about 5 years when I wasn't looking ans in love with being married.
I wish you the best and will be praying for you. In the meantime - find a darned good divorce attorney and let her kiss your butt as you slam the door on her. Don't try to 'fill the void' too soon, but do realize that she isn't the person you need in your life. Eight years is rough - mine was 14, so I hear ya there.