C# - Handle The Line Restrictions In Richtextbox?

Under RichTextBox_TextChanged event, I have
if RichTextBox.Lines.Count() > 2
{
//Message Box to display the user that you are typing more than 2 lines
}

so what i happens is when i have these data in

[0] - "East coast road"
[1]- "New York"

rich text box, when i click Enter, seems it goes into this state

[0] - "East coast road"
[1]- "New York"
[2] -""

and I get the message pop up box saying can't have more than 2 lines, however the last line is just an empty line? How do i handle the line restrictions in rich text box or how do i ensure that when the user clicks enter I don't move to the next line and move to the next line only if there is 1 line in the rich text box?This returns count as 3 where in there should be only 2, how do i eliminate that white space next line?