i just want to say (i come back) I'm back/I am back/I have come back/I have returned

I ended my relationship. (up a period of time loving a man .) Maybe the distance between us was (it is so) too far, (between us) so he chose another. (others .) I understanded (it) so (i) don't feel unhappy and (i) decided to have a new life. (.) From today, I will improve my English. (,) I am from China ,so if you (u) want to learn Chinese ,we can learn from each other. (,) The most important part is that you (u) can speak in (say) English , then we can communicate haha .Thanks ,welcome everyone.

Your writing can be easily improved by putting commas and full stops immediately after the last word (not leaving a space). You have one very long sentence separated by commas which can be reduced to several sentences so that it reads better. Your article is well-thought out and reads well - just need to address the punctuation issue.

I just want to say that I am back.

I have recently ended a relationship with a man. Maybe it was the distance between us, may be he chose another girl.

I understand it and don't feel unhappy about it. Anyway, I decided to start a new life. From today, I will improve my English. I am from China, so if you want to learn Chinese, we can learn from each other. The most important thing is you can speak English in order to understand each other haha .Thanks and welcome everyone.

i just want to say i have come back

I ended my relationship with my boyfriend.  Maybe it was so far between us so he chose another woman. i understand it so i dont feel unhappy and i decided to start a new life . From today i will improve my English. i am from China ,so if u want to learn Chinese ,we can learn from each other ,the most important is that u can speak English ,we can communicate haha .Thanks ,welcome everyone

commas work like this: thanks, everyone   not thanks ,everyone