Your paralegal/lawyer could be spot on depending on the law in your state. I am a lawyer myself, and though i do not endeavor in that field (domestic law) myself, i am conversant enough in legalese and did enough legwork myself during my own ordeal to know the ins and outs. Bottom line is that in some states... SOME states, mind you... adultery (if it can be "proven", which is not always easy unless you hire an investigator to gather the evidence) is an absolute bar to spousal support being awarded. There are other ramifications, too, including possibly custodianship of the kids, i believe. UNLESS, that is, you "consent" to the relationship by allowing it to go on without objection (And what you have to do to "object" may also depend on your state). At any rate, your lawyer is absolutely right that if you "know about it" (and in your case it sounds like EVERYBODY knows about it-- sorry) and do/say nothing, you may be waiving substantial rights you would/will have down the road (along with any leverage over her that such rights would entail.)
You really need to have a detailed convo with your lawyer about that aspect of it... know your rights.
Good luck!!
H53/W51, R-ing 4/'18
"Do not arouse or awaken love until it so desires"-Sg.of Sg 2:7
"So oftentimes it happens,that we live our lives in chains, & we never even know we have the key"-Eagles III 1:3