Oh dear OP!
You come across like you just don't get it...
So, you've clearly had intentions of cheating - whether you went through with it or not, the intent was there by taking a condom away with you. If my DH did that I'd be feeling utterly devastated. The intent to cheat is enough to kill off any trust in a marriage.
The fact that your sex life has dwindled... guess what? That's life, that's relationships. When the honeymoon period is over, most couples don't go at it like rabbits several times a day. The fact is that people get sucked back into the drudgery of life - work, housework, kids, family, other commitments. They're all a physical and emotional drain and ultimately sex will suffer for that.
Add that to the fact that you've clearly made your wife feel worthless by the intent to cheat and the fact that you can't seem to give up porn, which is another debt to her self esteem.
Do you think your wife wants to shag you when you're making her feel like shit? Making her feel like you have no interest in her other than housekeeper and a hole to shag?
It all boils down to the fact that you've likely made her feel like shit and that is probably why she doesn't want to have sex with you. You've broken her trust and shown her that you're happy to watch and wank over slim, sexy, unrealistic women on a screen and that you've shown that you're willing to stick your dick into someone else if the opportunity arises.
Do you think that the woman that you're supposed to love, honour and cherish deserves to be treated like that?
She's busy raising your kids, which is exhausting, physically and emotionally and you're sowing your gratitude to her sacrifice of herself to your family by fantasising about other women. See how that would put her off any intimacy?
You can't MAKE her trust you but you can pull your head out of your arse and stop making this about you and the fact that you are unhappy with your sex life. I can't imagine that she's particularly happy either. You need to show her that you can be trusted and stop expecting her to wake up one morning and have forgiven you.
Your actions have caused this. Stop blaming her for not wanting to shag you and behave like a responsible adult, husband and father.