Kim, it sounds like your boyfriend is telling you what you want to hear, or telling you things to try and make himself look like less of a 'bad guy'. If he didn't want you to have an unhappy ending he wouldn't have cheated.
Here is what I recently wrote to a woman who had a problem with her husband viewing porn (DVD and internet);
This is a tough question and the answer varies with the individual relationship. Some men look at porn the same way they look at football, race car driving, they can look at it all day, every day and it is nothing but pretty pictures and not a part of their "real" life. It's like women drooling over Denzel or Brad Pitt, we know we can't ever have them, but it doesn't hurt to daydream. With men, it's even simpler than that.....rarely are they looking at a woman's personality, or do they care what she's thinking, they are just looking at a pleasant (albeit stimulating) landscape.
Other people believe that looking at porn will make a man more likely to cheat because he will see things that he wants that he might not get at home. I'm of the opinion that if a man is a cheater by nature, then he will cheat. He could be with the most gorgeous woman in the universe and he will still cheat. On the other hand, if a man is a good man, all the porn in the world won't change that.
If you're considering that there is some type of competition between you and these 'actors', its like saying you think that he will seek out one of these women in order to be with them, which doesn't make sense. You have to ask yourself, is it the pron you want him to stop? what about other online sites that show women? what about movies that show female actresses? Men look at most women in a sexual manner, it's just the way they are built. Looking at pictures or films is not going outside of your marriage because these things are not real (in my opinion). You have to decide if you really trust him, or if this is something else thats bothering you.
You can't base your beauty or worth on other women. This seems to be a self esteem issue with you, even in your first question you talked about her being a model. If your boyfriend was with you for 8 years, there must have been something about you that he liked and was attracted to right? I would consider looking into therapy, talking to someone about how to boost your self esteem and learning to love yourself.
You asked if it's worth trying for a second time, but it doesn't sound to me like he's even interested in trying for a second time. It seems to me like he's moving on with this woman and giving you excuses about it. If he would be willing to leave this other woman and go to counseling, that's one thing, but telling you he doesn't want to hurt you means nothing if he continues to hurt you. I don't know if what they have will last, or if she will leave, there's no way to know except to wait and see.