Neighbor Visits Too Much?

I am a 32 year old working female and live in a bachelor apartment in a house which is divided up into similar apartments.

For the past 2 years a girl from another country has been renting an apartment in our house while working on her PhD at the local university.

Last year the landlady introduced us to one another as we are the same age, we started working out together after work 3 days a week. Soon I became an emotional crutch to her as she had no friends/family/support being in a foreign country.

This year I started cycling so we don't get to work out anymore. My problem: She whatsapp me up to 4 days a week and asks if she can come over and then she stays anything from 1 hour till well after midnight.

I cannot say that I am not home because: I have street parking, she can see my car. She can see my lights are on and she can hear when I open my security gate when I get home (she lives above me).

I am too scared to open my whatsapp to check chats with other friends as she will see that I am online.

I love spending time with friends and I love having alone time as well. Especially after a day working in a busy doctors practice. I listen to sick people moaning all day and love my job, but when I get home I want peace and quiet. Neither of us speaks English as a first language so it is very tiring after a busy day at work to deal with this. It has gotten so bad that I switch off my lights, park my car for the night around the block just to say that I am out (on a weeknight when I just want to rest and watch series) I feel like a prisoner in my own home. Lately she must have started sensing I am irritated because she has started sending messages that she made food or bought me a treat and wants to bring it over - which makes me feel obliged to say yes.

Half of her family is ill and she is fretting about not being able to be home with them, and about people annoying her at university, etc. Now she is moaning that once she gets her PhD that she won't find work as she will be overqualified. Why put yourself through this then? She moans 95% of the time and its really bringing me down and I am scared it is changing me into the same kind of negative person. She keeps crying about her situations and I really cannot relate. I myself have spent 5 years working abroad before. I managed by compartmentalizing my longing. I don't know why you put yourself through things if you know you can't handle it.

It is getting to a point where I am looking for a different apartment, but why should I move? I live 1km from work and love my place.

She just told me she is not going to finish her PhD this year and will have to come back for another year. I cannot deal with this for another year and refuse to move. I have been telling myself I only have to play nice and bite the bullet for a year, until she told me this news. It felt like a punch in the gut. I feel sorry for her, but I want my life back. I did not sign up to be anyone's shrink.

I never invite her over, she invites herself enough. I don't see how she does not get the message. I would sense immediately if I was annoying someone. Hinting does not help with her.

How do I set boundaries? I don't want to lie, and I don't want to be rude. She keeps telling me I am her only friend here.

Please help!