Story layout help, please?

Okay, so I'm trying create this layout for an upcoming story of mine, but I'm having trouble making it exactly how I want it to be.



That's how it currently looks like. I want the bottom right corner to be sharp as well, but I have no idea to do that. Anyone know how to? :(

I tried adding a border to the text so that the corner could be sharp as well, but it didn't work. Ugh, this is bothering me so bad. Idk, I'm getting annoyed.

Thanks in advanced to anyone who helps! xox