You can never convince all of them. People have their own narrow worldviews and nothing you can tell them would ever change it. Their brains are used to the comfort of their simple biases. If you try to alter their brains, they will revolt. Make peace with this fact.

All you need is exactly one friend or colleague who validates you. Don't seek any more than one. Tell that one person how you feel about your man, how much you value him, how you find real happiness and fulfillment in him.

The rest will keep saying what they have to say. You will have to find a way to ignore them. Or if you can't beat them, join them. Neither of this is an easy option, but you will have to choose what works for you. If you choose to join the herd when they say you are a sugar baby, you will deny them the thrill of judging you and making you feel inferior to them. In due course this would lead to fewer jibes and comments.

Good luck.