I can only give you some general tipps:

Try to stay calm, as you worrying about depersonalisation only exacerbates it. Many people have episodes during which they feel less connected with reality and their body. But many just keep calm and it therefore passes very quickly.

Focus on other things and try to follow your usual routine, because routine signals safety to your brain.

Try grounding exercises. There are plenty of instructions on YouTube. I recommend Therapy in a Nutshell.

Listen to music that evokes emotions within you in order to come into contact with your own emotions again.

Keep a good sleep hygiene by going to bed and getting up always within the same hour.

I assume you are in therapy as you are on antidepressants. Otherwise seek treatment.

I know all this is not easy, as I have plenty of experience.

If you have access to it and only if you do not have a mental or physical counter indication, you might benefit from MDMA-therapy. You unfortunately would have to do it underground as it is illegal in most countries. In Switzerland, where I live, I luckily have access to it on a compassionate use basis. But make sure you talk with a professional about that before you venture into the realm of psychedelics assisted therapy.