The designer was found dead by her assistant on March 17 of apparent suicide. Jagger, who was in Australia when she died, released a statement on Facebook, reported Ace Showbiz.
"I am still struggling to understand how my lover and best friend could end her life in this tragic way. We spent many wonderful years together and had made a great life for ourselves. We spent many wonderful years together and had made a great life for ourselves," Jagger, 70, wrote.
"I have been touched by the tributes that people have paid to her, and also the personal messages of support that I have received. I will never forget her."
Previously, a representative for Jagger said that the rocker was "completely shocked and devastated by the news."
The Rolling Stones' seven-date tour in Australia and New Zealand has been postponed "as a result of the death of L'Wren Scott."
Jagger's model daughter Georgia May Jagger also cancelled her appearance in a modelling gig in Melbourne following the sad news. She reportedly headed back to the US to be with her family.