External drive is damaged and freezes my Mac. Any way to recover?
First Steps: Repair the Disk, Tell Us What Happens

What exactly is happening isn't something I know. However, with a damaged disk, the first step should be to attempt to diagnose/repair it. Since that didn't work, tell us what went wrong. It'll give us a lot of insight into what may have happened and how we can fix it.

Since You Can't Repair The Disk

It's possible (although unusual) that using the command line fsck will help. Follow this guide and let us know what happens.

Command Line?

This doesn't seem like it should work, but if the disk is accessible from the command line, you could just use command-line copy paste. This doesn't seem like it should work, but you never know.

Data Recovery

No one likes it, but you may have to just reformat your partition after taking it to a data recovery service.