Of course it is a double standard, stemming from the obsolete but still rampant paradigm in which a woman is a chattel, a possession. She has no right to share any part of herself with any man besides the one who owns her, and if she does, what she is guilty of is theft.
The puritanical flamers need to get over themselves. There is nothing universal about the standards they are trying to impose, all religions notwithstanding. What they’re doing by condemning you is far worse in my book than what you did.
“Cheating” is the concept that needs to be reexamined. A relationship, whether personal or business, is a set of mutually agreed-upon expectations. If you promise not to kiss anybody other than your partner, then you do kiss someone else, you violated the terms of the agreement, and you need to deal with that together.
But each relationship stands on its own and has to be negotiated on its own. There is no universal rulebook that says every sexual relationship must be structured in a certain way. I am hopeful that your generation will help move human culture forward by redefining marriage, family, friendship, and all the many ways there are for us to be together.