Moral Dilemma

I am suffering from a moral dilemma of sorts, and I cannot quite figure out what to do.  You see, it involves cheating of the sexual variety.  Normally, I am absolutely opposed to even the notion of cheating, but this is a very odd situation (aren't they always?).

Me: I do have a current boyfriend.  He and I have been together off-and-on since late June, so almost 7 months now (longest relationship I have ever been in).  However, during that time, he has dumped me 3 times, refused to talk to me for over a week during the holidays (more on that later), and made me cry countless times.  Oh, and we still have yet to have sex.  He tried to fuck me exactly twice: on our first date when he tried to invite himself around to my place after he got drunk at the bar, and when I invited him around to my grandparents' house when I was house-sitting (and yes, he was drunk then too).  I have attempted to make plans to fuck him, but he broke up with me the night before the first time, and he had just recently started talking to me and made no attempt to revive our plans the second time (and shot down any of my attempts to revive our plans...I really shouldn't have invested in special underwear just for the occasion, ridiculously frilly shit that makes me want to vom but that he'd like because he's conventional like that).  He stopped talking to me because he had a paternity scare with his ex, who he had post-break up sex with less than a month before our first date, meaning that I am more or less the rebound from his pregnant ex (the baby isn't his, by the way).  He still refuses to claim any role in having ended up in his paternity scare ("it could happen to anyone"...yet he had sex without a condom, and when a man has sex [especially without a condom], he runs the risk of getting a woman pregnant).  This all tells me that he isn't really mature enough to be having sex, since he can't deal with the consequences, and he may very well not want to have sex with me unless he has beer goggles on.  There's also a ton of other shit that points to him being socially immature, and he never demonstrates his alleged love for me (choosing, instead, to demand that I provide evidence that I love him to prove that I love him as much as he claims to love me).  I do love him, and no one is perfect, but I don't know if I want to wait around for 5-6 years for him to get his shit together enough to be father-of-my-children material.

Really, I should dump him, but I have put so much damn time and energy that I dislike having to leave without seeing anything in return for my investment.

Potential Partner: Here's the thing that makes it truly a difficult decision.  The potential partner in this adulterous scenario is none other than Fresno Boy.  Now, I haven't fucked him in a year, not since our plans in April fell through, but he contacted me in late October/early November asking for sex (incidentally around the time of my third break up).  He is sexy, and the sex is fantastic, but that alone isn't enough to convince me to hop into bed with him.  However, the fact that he clearly needs to get rid of his current psychotic girlfriend (as evidenced by her social media accounts) has led me to think that he may need a sextervention.  I almost feel guilty, like if I had managed to fuck him in April, he wouldn't have been so desperate to end up with her (he contacted me around the time that she posted a picture of them as a couple on her Facebook...so clearly she hasn't been enough for him since the beginning).

It is only sex, there is never anything emotional involved really, beyond a basic level of trust, with the minimal level of caring that goes along with knowing that person can trust you.  I highly doubt that she knows about his fetish either, and fetishes are always itches that need to be scratched at least once in a while.

So, there I am, in a problematic situation with no easy answer, really.  Do I stay in a miserable relationship, just for the sake of praying for the boyfriend to eventually grow up and maybe find me sexually desirable and worth loving someday, and continue to be the faithful girlfriend, do I dump the boyfriend and engage in sex with Fresno Boy, allowing him to realize that he doesn't have to be shackled to a psycho to get laid, or do I cheat?