There is no risk here at all.
STDs are not transmitted by hands.
The only way to get STDs are:
* oral sex - your mouth on someone's genitals, or their mouth on your genitals
* direct genital to genital contact - this is unclothed vagina to penis, penis to penis, vagina to vagina contact, or penis to anus contact. If penetration isn't involved, some intense rubbing and grinding without clothes on needs to happen.
* anal sex - penis in the anus penetration
I'm not sure why you have such anxiety about this, but anxiety and/or guilt doesn't equal risk.
Here are some posts from our experts (when we had them) that may help -
https://
www.medhelp.org/posts/STDs/Nervous-about-mutual-masturbation/show/2183476
https://
www.medhelp.org/posts/STDs/Mutual-Masturbation-STD/show/1968429
https://
www.medhelp.org/posts/STDs/mutual-masturbation-sti/show/1858544
https://
www.medhelp.org/posts/STDs/Understanding-the-risks-of-mutual-fingering/show/1516796
https://
www.medhelp.org/posts/HIV---Prevention/Vaginal-fluid-on-hand-touched-inside-of-condom-and-head-of-penis/show/1119533 - read this thread thoroughly. There is an excellent explanation about why certain activities are not risks, and why others are.