I have experienced cheating once and I dealt with it by promptly dumping my boyfriend and getting on with me life.

I haven't personally dealt with it in a long term relationship, but my husband had handled it with exes by just shutting himself down emotionally and knowing that any potential for an actual future with that person (marriage, kids, etc) would never happen. He'd just stick around and try to avoid any talk of the future since it was easier most of the time to just shut down and avoid the fighting.

I have never experienced cheating, but I have experienced an almost cheating sitution paired with lying and sneaking around... In that situation I tried and tried to get over it, but the trust had been broken either way. I had to move on. Once my trust was gone so was the foundation. I had to shut my emotions off completely which in turn made me ask myself " If you dont trust this person and now you have non emotional attachment why are you here"

I have since moved on into another relationship

I actually wrote an article about this on EdenCafe- if you're interested in reading it, it may help you gain insight. Cheating, in a broad sense, is tough. It really depends on the situation of both partners.