Well, first off, you still have an O/S on the SSD, and Macrium R has to some extent protected you.

As to what you do next- well, it depends how important the content of your HDD is, and whether you have already got backups of everything on it.

If you have, discard it (appropriately) and replace it.

Note: if you had been using disk imaging with MR routinely and regularly to image that HDD, the CRC check MR performs would likely have given an early warning- at leat that's what happened to me.