Tricky one.
My ex husb cheated on me twice. We drew the line at sex being the ultimate betrayal. Having our 2 ds to think of, I took him back after the first time, gave him a second chance, him swearing full sex didn't occur. It ate at me 24/7, the text messaging, the illicit meetings. I loved him and was so blind.
We managed to stay together, though I never got over it, for the next 2 years. He received my full trust (yes, what a fool I was), and then he promptly walked out the door after he'd been having an affair with the polar opposite of me for God only knows how long. I never got the full truth.
Even now, 4 years after the first betrayal, I hear snippets of info from his ex work mates who think I know the whole truth "he used to shag her in the work toilets". It still cuts at me, I was hospitalised because I'd got so thin, bringing up my twins, and working part time. Anytime I mentioned him helping out with the housework, he was off out, no doubt for his ego (or body) massage.
Now I find it difficult to trust, I have a DP and we both agree, even the illicit meetings lead to things. Complete openness and honesty or I'd rather be on my own.