Why is my phone ink always spread on my screen?

@benjaminanaman your phone has an AMOLED. Display. When these crack they leak. The only way to repair this is by replacing the screen.

Since iFixit does not yet have a guide for this, use something like this video to replace the display. Replacement displays are available at many online stores.

While you work on your phone, take lots of pictures. Once you are done with it, take those pictures and create a guide for iFixit. That will help the next person that has the same problem as you do. It's easy and fun to create these guides. https://ifixit.com/Guide/new The iFixit community will appreciate this.