I know what it is to want something with your whole heart. I wish you all the best! If it helps, try to look at your cover letter through their eyes. What would you want to see, if you were hiring you? Sometimes, being overly emotional isn't the right way to go. (But, being passionate about your work is great!) So, strike the balance between your head and your heart. I'm sure they'll see that and realize what a "catch" you are!