You truly raped your PC. You created a great mess. Well, at least you don’t mind both storage media being deleted, as it seems.
Follow one of the dual-boot tutorials here:
If you install to 2 different storage mediums, then remember to install only a SINGLE GRUB! Don’t install GRUB on both storage mediums. Then it will work.
Additionally, follow each single step of the tutorial you choose. Don’t skip steps. Don’t add steps. Just follow the tutorial step by step. Precisely.
If you do this, then everything will be alright.
Before doing that I would recommend wiping your storage media (as it seems like you don’t need the data on them) and then start anew, using a dual-boot tutorial, from scratch. This includes entirely reformatting both storage media (i.e. deleting all data from them).