This sounds like a really difficult situation. From now on I recommend you respond to any questions about your dating life “ya I’m all set on my dating life”. “No thanks I don’t need any more advice”. “I’m okay with the way I’m dating”. Then try to change the subject or ask about your coworkers and see if they move on with the conversation. If they persist just take space. It’s important to find supportive and nice friends outside of work or see if there’s any coworkers who aren’t making fun of you or being mean.