Permanently Replacing "comment_notes_after" Fields

Greetings,

Here’s my problem. When I share my blog post on Facebook I get all these HTML tags that go under the comments field –

http://s19.postimg.org/3roq8t87n/FB_WP.jpg

I searched for a solution but non of them helped me remove the tags from the Post when I share it on FB. I was able to remove them on the blog itself, but somehow they still show up when I share it on FB.

I use Rustic theme.
Here’s my website url – http://www.fractalseverywhere.com/

Solutions I used to remove the tags were all about adding code into Comments.php, like this one –

<?php comment_form(array('comment_notes_after' => null)); ?>

So basically editing Comments.php doesn’t help.
I looked into editing comment-template.php in wp-includes, but since so many advise against it I didn’t attempt it.

Also, I would like to put something else instead of the Default – “You may use these HTML tags and attributes…”, a line of text that would say something “If you like this post hit Share or Like it”.

AND, I would like to make it a permanent change, so that the next time I update the theme I don’t have to go into code again. I’ve read this can be done through creating a Child theme, but since the edit might be in wp-includes, I’m not sure how to do that.

Ok, this might be a bit tricky but I hope someone will be able to help me with this.

Thanks in advance.

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