Ok a few things i would do.
1: if i loved the guy and trusted him beyond these allegations : i would : let it go over my head easier said than done obviously but whats more important some idiots trying to hurt you or your relationship
2:If i had doubts and didn't trust him: in all honesty : i would go and confront them not in any "why did u say this" etc i would approach in this sort of way..
'im probably worrying over nothing but i feel i have to say something because its been niggling away at me for some time, i recieved a text saying *your partner is cheating, now maybe this was a prank im quite unsure what to think is there abny way you can clear this up.
QUESTION
From what i can gather this seems to have affected you in a big way, my question is if your partner is aware of this and he's 'innocent' why has the thought of confronting the individuals entered into his head.
anyway hope this helped and good luck