Regarding the specific claim you mentioned, it's important to approach it with skepticism. The quote "haters gonna hate" is a colloquial and modern expression that originated in contemporary pop culture and is commonly used in informal contexts. It is highly unlikely that Albert Einstein used this phrase in a letter to Marie Curie.
If ZME Science published a letter of encouragement from Einstein to Curie, it's crucial to evaluate the authenticity and credibility of the source. Letters between prominent historical figures can be found in archives or published collections, and it's always advisable to refer to well-established and reputable sources for accurate information.
If you are interested in exploring Einstein's correspondence with other scientists, there are various collections of his letters available, such as "The Collected Papers of Albert Einstein," which can provide valuable insights into his interactions with his contemporaries.