If you're truly bothered that you failed to hold on to yourself and feel the lack of integrity because you sold yourself out, there's only one solution: pay the price to get your integrity back. 'Fess up that you need multiple relationships to feel fulfilled and deal with the consequences.
If you don't need multiple relationships to feel fulfilled, stop beating yourself up over the matter.
When speaking of various forms of non-monogamy...it ain't poly if you're just fucking around.
While polyamory, open relationships, and swinging are all distinctly different approaches to non-monogamy, they are not mutually exlusive. Folks can, and some do, engage in more than one of them at a time--and it's all good.