Why make it stop? Even if the first set of exports is continuing, you can export a second set of photos. I'm afraid I don't see a Lightroom issue here.
You can stop those 7500 pictures to export and restart it at a later time or you can simply start a new export stream. It's your decision.
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You have somehow selected all the images in your catalog. Stop that export. Remove the exported images and Delete then from the disk if you chose to.
Then Start a new Export after you have selected only the images you currently want to export.
It clearly states how many image are selected for export at the top of the export dialog window. Please read all of that dialog window before you click the Export button at the bottom.
LR does not arbitrary export image you the user have not specifically selected.