Managing Stress at Work/School

What would you do. I work for a company where I trained this guy to cover me while I was on long term leave, about a year. On coming back he is now training me on the same stuff. The problem is he's really patronising, always saying I don't wanna give you too much to do, how you getting on (every few minutes), etc. He's acting like he's my manager. When there's something challenging to do he tries to butt in when I'm already dealing with stuff. He has to get his pennies worth in. I'm so easy going never had a problem like this but he's stressing me out big time. If I have ideas and make the mistake of mentioning to him he says we shouldn't do it until we check with our manager! And this is for simple common sense stuff that doesn't need authorisation. I'm permanent and hes a contractor, dunno whether he feels his job is threatened with me back and no approval for additional head count. He butts in even when I'm having a chat with another colleague. I think he wasn't expecting me back. What do you guys think I should do?

What happens when so much pressure is forced on you by external sources and other individuals that you cannot take time to relax/destress/heal yourself or breathe?