Yeah, knowing eachother for so long and cheating are both going to have some ill-effects on the experience.
I hate to say it, but if you hook up more in the future, it will likely only get better, as you get more comfortable with the ideas of cheating and of being with eachother.
I say I hate to say that, since cheating is clearly not a great idea. Not judging, just saying it could get really ugly, especially with kids involved...on both sides.

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MichaelBlue