So sorry about what you're going through. Anyone who would secretly let someone risk a serious disease is absolute scum.
You've correctly identified the major flaw in "unicorn hunting" (a couple seeking a single person to be with both of them equally), and your experience is one a lot of people have had versions of, unfortunately. There are wiser couples out there who understand how to let a new partner be his or herself, so it's not all bad when it comes to poly and couples, but you do have to be careful.
I'm sure what you felt for Jay was real, but try not to romanticize it too much. In the end, he wasn't willing to take a risk to be with you. Instead, he's standing by a grade-A prick (does he know Bob deceived you about his status?). You deserve a better, braver partner.
Bob will indeed probably keep doing this. All you can do, if you have related social circles at all, is be frank about your experience. But what's really important right now is you living your own life and putting this crap behind you (hopefully!!).
Me, 30ish bi female, been doing solo poly for roughly 5 years. Gia, Clay, and Pike, my partners. Davis, ex/friend/"it's complicated." Eric, Gia's husband. Bee, Gia and Eric's toddler.