Was I hacked in my whatsapp for this?

I did the stupid thing of give my whatsaap to a stranger I met in internet. One day that this guy sent me a message I noticed for the first time that I couldn't see if he was writing or recording an audio while he sent me his messages.

For this, I know that exists whatsaap offline, and I thought for a while that he could be using it (although all the applications for hide you while you are writting, have not the option to send recordings, thing that made me think that receive a voice recording of him without seing him connected was a lot weird).

But then, what made me suspect is that I stopped to see online my other contacts while they were writting me, not only him. When I realized about this I knew that was something wrong here, but I haven't do anything about it since that time.
I was hacked in my whatssap by this person? or why did it happened?
What can I do?
Thank you very much for your helpful responses.