so lets change the pattern to and give a try:
^.*\r?$
for working with regex have a look here:
However it is recommended that you will collect of text variations and share the set with us. Based on this we can work out the most close matching solution approach. Here we want just check if regex or
YourStringVar.Split({Environment.NewLine},StringSplitOptions.RemoveEmptyEntries)(0)
will better match to your case