Oh my, that sounds really stressful, especially when you’re just trying to work and suddenly feel accused of things like rumours. If I were in your shoes, I would try to stay calm first and clarify directly with your boss in a neutral way, like asking what exactly was said and how it came about, so everything is clear and not based on hearsay.
At the same time, I would also start noting down any incidents or conversations just in case things escalate, so you have clarity and protection for yourself. Workplace politics can be really draining, so try not to carry it all alone and confide in someone you trust outside work if you need to release the stress.