Can I legally open window on wall facing owner's plot?

I have purchased a 10' × 15' (150 sq. ft.) room from a landowner, located in the middle of his plot. Earlier, I had a door that opened inside his plot, but due to disturbances caused by him, I closed that door and instead opened a door at the back, which opens outside of his property. Now, I need to open a window on the wall where the old door used to be (facing the inside of his plot) for ventilation purposes. However, the landowner is not allowing me to do so. He says that nothing belongs to me on his side of the property. Additionally, he is using both side walls of my room but has not constructed his own walls. He is also using abusive language and threatening to physically harm me and my family if I try to open the window. What are my rights in this situation? Do I have the legal right to open a window on the wall where the previous door existed? Please advise.