Be sure to wave and say Hi every time you see her, whether your with a lady friend or not. Walk over and strike up a conversation about the weather. I have found that regardless of circumstances in life if you are polite and friendly people are less taken aback by your actions. Also, if I have the same lady to my place more than once I leave the door unlocked and tell them to just come on in when they arrive. To me it seems more natural that way. When they leave I step out the door and have a short conversation in plain view of anybody that wants to watch. Give them a nice hug. Making it look like we are besties. Above and beyond that I truly don't give a shit what my neighbors think.
Her terrace is opposite my front door and she is always sitting out there watching. A few times i have had pretty escorts visit and she and she watches them enter my place and then watches them leave. I fear she is going to spread gossip about me. How should I handle this situation?
You mentioned doing outcalll a few times, but you didn't say over what period of time. I wouldn't be worried if the time period was a few months. If it's a few days, that's another story. So it's hard to get a handle on the situation.
Also, you didn't mentioned whether these were first visits or not, or whether these were well reviewed providers. I myself, prefer to do incall on a first session, even with a well reviewed escort, but that's just me.
Worse case scenario, you could always move and look for a more secluded apartment where neighbors couldn't see your activities. OK
You can't control her or what kind of gossip she spreads. You can do incall or get a hotel. You could try making her a glass of sweet iced tea and sitting down with her, ask if she has seen all the beautiful women that have been coming around and tell her your nailing everyone of them she'll probably never look at you again.
....her balcony doesn't face your balcony...giving her a show might turn her off and she'll give up watching your movements.
MsManae
P.s. I love the thrill of possibly being caught.
So, you are the stud muffin kicking it with a bunch of pretty women. You should tell one of your visitors to dress up as a nun. That will get the gossip going 
Party on my friend.
Be sure to wave and say Hi every time you see her, whether your with a lady friend or not. Walk over and strike up a conversation about the weather. I have found that regardless of circumstances in life if you are polite and friendly people are less taken aback by your actions. Also, if I have the same lady to my place more than once I leave the door unlocked and tell them to just come on in when they arrive. To me it seems more natural that way. When they leave I step out the door and have a short conversation in plain view of anybody that wants to watch. Give them a nice hug. Making it look like we are besties. Above and beyond that I truly don't give a shit what my neighbors think.
She is probably lonely. Maybe give her a little entertainment every once in a while.
She'll either go inside or come over and visit you with a bottle of champagne.