Hello,
Really the best way to deal with this is to contact bbeng89 through the add-on's support page and ask him to offer a solution. He might be able to help.

I did post to the support forms he has. I went into my files and deleted it from the site. But it still shows up in my dashboard. I tried to uninstall it by clicking the edit button but it reloads to the top of the page.

I realize you were in a panic to get your site back up and did the natural thing of deleting the files but I'm afraid you will also need to remove the add-on from the database as well because concrete5 still thinks you have the files there. It looks this up in the database and sees references to these files and goes looking for them. I'm not sure how much experience you have with altering the database but if you feel comfortable, I would try making a backup of the database first and then removing the add-on from the 'BlockTypes' table to see if that kick starts things.

mnakalay is likely on to the correct solution. There is a big warning on the add-on's marketplace page that says it needs at least PHP version 5.3.

Sometimes you can change the PHP version in your hosting plan's Control Panel. Have a look under something like "PHP Versions".

Actually I didn't look at the error properly.

Here's what I think. The function called that's throwing an error calls the method DateTime::diff() which was only introduced in PHP 5.3

So my guess is that you are using PHP 5.2.

If I'm right, ask your host to upgrade you to PHP 5.3 and everything should be fine.