The question you should ask is whether the language rises to the level or harassment/coercion/intimidation, (directed at the tenant or in such a way that creates a hostile environment), or if it is a matter of free speech.

I owe a duplex in rural Illinois with an inherited tenant on one side. This man doesn’t take care of the place and has a drinking problem. Recently a single female tenant moved into the other side and on the very firs...

He creates problems quite often. 1-2 tenants have left previously because of him, one has called the police on him as well once for harassment.

I could harass my real estate agent for some of the info, but I hate to bother him on an off market deal since he won't be getting commission.

I just don't want to be harassed.

But that's likely not required in this situation, given how close the landlord and tenant are.The landlord should also be careful not to harass the tenant. 

Also, there are folks that have had the same cellphone number for many years and when it comes to tenants and such,  wouldn't want them to have their direct cellphone number so as to not be getting calls at all times of the night and if I happen to one day get an irate tenant who I would need to evict, now that person has my direct cellphone number and can start harassing me, just because. 

To say the other team is harassing us is an understatement.  

 I'm not a lawyer but seems to me any further contact would give her ammo for a harassment charge and I have a hunch it wouldn't be the first.  

Shut him down pretty quick when he threatened to let his attorney to sue me for discrimination by telling him i  have attorney too and let your attorney talk to mine, if he is going to call me again, i will sue him for harassment.