Can I Have A Visitor Who Is A Felon?

Your land lord has no right to tell you who you can and can't have over it is none of his business. that is your decision and if your landlord has a problem with it then call the police and they will tell your landlord the way it is.

First of all, you have a right to privacy! It is none of your landlord's business what you do. You pay rent and he is responsible for the upkeep! Someone stays over they are not considered living there until after 2 weeks. Even those have claws depending on you agreement about pay.
As long as police are not raiding you and you are not a nuisance to your neighbor hood with trafficing and disturbance.
You can research on a book called Know your rights for renters and landlords.
Tell your EX to come on buy, but if your landlord is your neighbor and he feels he can tell you what to do make sure your ex has no warrants that way if he were to call the cops you all can have a great laugh at your landlord's expense and it don't end up sour due to the warrants.

I would tell the landlord that he cannot tell you this, and to mind his own business. How did he find out about this anyway? While you are at it, talk to your landlord/tenant board about it. Hope this helps.

You can have anyone you wnat over. Its not like anyone walks around with a sign advertising his criminal status.