I would like to know whether the expression this is the thanks I get? is used in English or if there is any other expression conveying the same meaning
The implication is that one shows no signs of being grateful after someone did something good for him/her or one is flabbergasted at another person's ungratefulness or ingratitude after being bighearted and generous to him/her.
I haven't found a specific entry in an English dictionary to back up this assertion.
But the expression appears in the Collins English-Spanish dictionary in the word thanks and the Spanish equivalent conveys the meaning that you have stated
[EN] that’s all the thanks I get! - [ES] ¡y así se me agradece!
I've also found these lyrics from Wilco, a rock band from Chicago, Illinois
Is that the thanks I get for loving you?
Is that the thanks I get for telling you the truth?
you say you wanna know
Where I go when I go
You say you wanna communicate
But you don't hear a word I say
It seems that the speaker thinks that his girlfriend is not thankful enough.
So ... I think that yes, it's used.
This is/That's the thanks I get? or: Is this/is that the thanks I get?
The expression is used all the time in English. The trick is knowing when to use this and that here.
If you are talking to a person who was not grateful, you would use This. If you are referring to a person who is not present and discussing his/her reaction to it, you use "That's" or "Is that".
