Shit, how awful. I really feel for you. So sorry love
I think you know the truth of whats been going on here. Such a horrible, sad truth, with SO many implications. For you, and your childen. I don't mean about them having possible contracted it congenitally, I think it unlikely as you've only just tested positive for it.
If you had a negative test 18months ago, you can completely rule out that it was you that had it via your mother - hugely unlikely, anyway, as you'd have had some symptom before now. Additionally, having it for that length of time, would almost certainly have caused infertility.
You've had no intercourse with another man for 22 years, and prior to that, there had been no -one else anyway. So, you can completely rule out that you or any other man is the cause of it. ( I realise you have already done this, i'm just trying to be pragmatic here)
So, other cause is your DH. He may have been infected with it before he was with you. Although, again, very unlikely that you would have tested negative for it 18months ago. There is not really anyway, that had he had it all this time, that you would have only just had a positive test for it. It would have shown up long before now.
THe only possible source of the infection is your DH. This had to have happened some time in the last 18 months.
He cannot refute the evidence, you are currently being treated for the evidence of his infidelity. He has definitely given it to you, and he has contracted it from a women he is either seeing still or has had a relationship or someone he's randomly had sex with.
I am so so sorry WT. I know I've written this incredibly bluntly, but, It was more really so you can get it clear in your mind, perhaps present it to him i the same way? He simply cannot insult your intelligence in this way! How can he even suggest that you caught it any other way?
I guess, you are in the strongest position really, as you can now take your time, work out what you want to do, and put plans into place. Perhaps even do all of this first, decide if you want to remain with him, if not, then get yourself prepared for it. If you would consider it, should he tell you the truth, then you can have it all on standby.
You need to confront him again, with the facts, which are as I, and many others on the thread have shown you.
I just feel for you so much. What a horrible situation to be in. I'm afraid also, that i'd advise you to have an HIV test. THis is separate to all the other tests you've had, so wouldn't have shown up, unless they did do a blood test at the same time.
Shit, I"M just so for you and so incredibly on your behalf. Horrible, lying, cheating bastard, who can't even have the decency to own up to what he's been doing when confronted with such definite evidence.
Good luck WhiteTulip, you are in my thoughts so much.