Will a girl feel cheated/shocked if I express my love for her, then tell her about deadly disease that I had?

She will feel cheated when you have not confess to her. Why? Because you did let her know your feelings. Who knows she may feel the same way. If she loves you too, she'll understand and may care a lot for you. Of course, she may feel sad/shocked the first time she'll hear this from you. The important thing is that you are honest and you let her feel that you trust her. You may regret this for the rest of your lives if you don't have the courage to take the lead. I don't intend to hurt you, just saying what's on my thoughts. Don't think about the "end" cause everyone will be leading to that. Cherish every moments you two have and you'll find happiness w/ each other.