urcocknotmine, what you do next depends on what you think and/or hope can develop with this guy.
If there seems to be some real relationship potential here - even if that relationship is strictly that of a fuckbuddy or friend-with-benefits, then you have to tell him the truth. If sex with him is going to continue to be bareback, then you need to be up front on your viral load status at the same time as you educate this guy some on the real world risk entailed in topping a poz hole bare. If you are on an effective treatment regimen and have an undetectable viral load (or very low viral load), then the risk your top runs barebacking you is slight. Not zero, but very low. If he decides he's cool with that level of risk, fine. If not, fine. He may be one of those guys that can't handle even the idea of having any kind of sex with a poz guy.
I can see using the tactic of telling him that you've just tested positive but here again, if you think there may be a possibility that this man might become a friend, or a regular fuck, then there's a good chance somewhere down the line that he'll learn the truth. It's always worse when a falsehood is discovered long afterward than setting the record straight as soon as possible. It's not clear where you live, but not disclosing your status may be criminalized in your state. Having the truth come out much after the fact seems to make it more likely that someone who feels deceived would want to take revenge, perhaps legally.
I did see you chose the 'Don't Ask, Don't Tell' option for HIV status in your profile here. Many years ago I decided the stress and strain of disclosing in person was way too much drama, and have always made my positive status prominent in any profile I've posted. I'm sure it means that some guys won't give me the time of day, and in earlier years I'm sure it meant that I didn't get laid as much as I'd have liked, but the policy has saved me oceans of grief. These days I find neg guys much more willing to play. Still I've also had to make sure that guys actually read my profile, to be sure they know what's what.