I want to try my English by SMS this afternoon.

Foreign teachers are generally called dear Ms. Lin.

I really appreciate everything you have done for me. My mother, my family and I are very grateful to you. I'm sorry that I've always made you angry in the past six months. Please accept my apology. Sorry, I can't express this in person, because I am a shy person. I'm used to studying with you, joking with Mr. Lin around, talking about you unconsciously with my classmates (in a good way), being called "Lincoln, you are so close to Mr. Lin" by friends and being jealous in their glare. I think I regard you as my second "mother" now. I hate it when people turn their backs on you; This makes me very angry. I almost cried when we hugged tonight. Although I know this is only a temporary separation, I will still miss you very much. I wish you and Mr. Lin good health and good luck. May God Almighty bless you.

Always reply to you, (this foreigner didn't say that he always respected you, so I translated it directly. You can consider changing it to the more commonly used sincere/warm/yours/cheers/love/best regards).

Lincoln

Pure originality, reference: 7 years+experience abroad, hope to adopt.