We have been answering these questions for you for years.
If the skin on your hand is intact, there is no risk. Even if it isn't, if the person actually has genital herpes, they'd have to be shedding the virus at that exact moment, and shedding enough to infect the one spot on your hand where the skin is broken.
It would have to be the perfect storm of things. It didn't happen, I'm sure.
You have a cycle of cheating on your partner, feeling bad, coming here, asking the same questions, and freaking out.
Maybe - and no judgement here at all - find out why you continue to go outside your relationship if it makes you feel so bad. Counseling would be a good start.
Whitlow is rare - very rare in fact that around 2 in 100,000 people have it diagnosed which relates this to a risk of 0.002% chance. Even if they had HS genitially it does not mean that you would 100% get it. Whitlow itself is not considered a STI in itself.
My opinion is to move on.