Saving the textfield structure for custom channel

Hello!
We have built a custom workflow node that works as a digital channel. What it does is basically takes a message /markdown and sends it via API to our Webpage to a customer.

This is and example:

After sending the first one it looks good and has the correct spacing between the rows. But sending the next time and also clearing cache it looks like this:

What is the best way to save the structure from the first picture in this text-field?

Thanks in advance, Martin