So she's shit at her job, got the sack from her last place, but he hired her anyway even though he claims he wasn't bothered one way or the other and only hired her because his boss asked 'is she a looker?' .. to which your H presumably replied 'yes' otherwise how did she end up getting hired?
She apparently needs your H to 'hand hold' her through the work, to act as her partner in a 'double act' and to act as her knight in shining armour to 'defend' her from the unwanted advances and attentions of the rest of the male workforce. He's getting 'pats on the back' for hiring this beauty, but is himself oblivious to her charms. He goes away on overnighters with her but doesn't tell you because he doesn't want you 'to worry' and tells you, you've just got to 'trust' him.
When this vision of loveliness meets her boss's wife (i.e. you) instead of being friendly and engaging, she is unfriendly and won't make eye contact.
He talks about her frequently (despite knowing that it upsets and annoys you) what she says, what she thinks, what her hobbies are .... and he continues to recount all this to you, all the while knowing it pisses you off big time and all the while continuing to insist that he doesn't fancy her in the slightest. In addition, and despite having proof ('back up' I think you called it) that she is shite at her job, he then insists that despite her ineptitude, she is there for the duration?
This trustworthy fellow who is able to resist the charms of the 'looker' that every other bloke in the company is falling over themselves to get to, was forced against his will to sit through a private lap dance which he didn't apparently watch (but still 'lied and lied' through his teeth about, until confronted with the evidence of payment and could therefore deny no longer). This trustworthy fellow as well as paying for lap dances and hiring empty headed beauties who can't do their job, also has a penchant for ogling women and looking for nudes on the internet.
.......................................
That is effectively what you have told us OP but written in a different way. Same information but in a more 'factual 'format rather than a 'I'm not sure what to think/I don't know what to believe type way?'
Now imagine someone else had told you all that about their H? What would your response be to them?