P.S. das ist Funktion in Italki 

Hallo Zahra, hast du probiert community --> language partners? Ich habe jezt gefunden dort viele Leute, die Deutsch sprechen und Persian (Farsi) lernen moechten. 

I think everything depends on your goals and it should be your personal decision. I know quite well (I would say I speak fluently) 5 languages. Most part of my life, i.e. while I was in high school, I was simultaneously learning 3 foreign languages. It's normal in Latvia and in other parts of Europe. So not being perfect in 1 language and learning another one at the same time is ok. But you have determine, whether learning new language might disturb the language you have been learning.

For example, I used to study Spanish for 2 years. When I moved to Italy, I realised I should stop practicing/learning Spanish (I was not fluent in Spanish) for some time, as it makes very difficult and confusing for me to learn Italian, which I have been learning from 0. Yes, it helps to understand basics, but then I just could not remember which word is Spanish, which is Italian. Now, after I became fluent in Italian, I can come back to learning Spanish. 

I am also Leo 21/08 :)

Hotel XXX,

I have made a reservation [or "I booked a room in your hotel"] at your hotel from 10/17/ 2016 to 10/28/2016 via Internet [it's better to indicate which website, as most bookings nowadays are from Internet or just delete this], and the reservation reference number is XXX.
I would like to ask to you if there is a shuttle or a metro to/from for the airport XXX. My plane leaveS at 15.00 of on 10/28/2016.

Thank you so much for your attention.[it's better to say:] Thank you in advance! or Thank you for the information in advance! 

Best regards

Also beginning of the letter could be:
Hello,
Dear Sir/Madam,

rather than Hotel XXX

Good luck! ;) 

When I feel sad, it's good to write everything down, but afterwards, in order not to get too much into sadness, you need to get busy. Focus on the task which you have - work, hobby, fitness, cooking, washing - whatever, just keep your mind outside the topic which brings you sadness. 

Other option - you could have a coaching session. Coach could help you to get out of sadness and become happy again. If you still feel sad and need help now - feel free to contact me. I am professional life coach and could do a session for you for free. I have been in similar situation and there were great people who helped me. Now I would like to give back :)