The thing is that no one will ever see the divorce decree so he can tell people that he filed anyways. He will likely say it anyways, regardless what the paper says. He likely saying it now. He says he left you.

You have no control over what he will tell people plus everyone knows that who filed does not matter. It’s not always who initiated the divorce at all. It’s just legal language.

Of course his lawyer says he is filing for divorce. His lawyer wouldn’t say you are filing because he isn’t representing you. I never heard of jointly filing but maybe it’s being done when people get along. You two don’t see eye to eye (otherwise you’d be still married!) so doing things jointly will not work.