Khloe Kardashian got the horrible news a friend had died from a drug overdose yesterday -- all as she was returning from a vacation with her BFF Malika Haqq in Hawaii.

The reality star looked stunned and sad she touched down at LAX last night .

The bad news comes at a confusing time for Khloe as she's reportedly flirting with estranged hubby Lamar (click HERE to watch the clip). Khloe never finalized her divorce to the troubled baller, so technically they're still married and a source tells X17, the two are spending time together and MAY have even been together in Hawaii!!!

Along with the picturesque snap, Khloe wrote, "Hawaii, you were great to us! Thank you for the memories. Beyond blessed and I thank God everyday for granting these beautiful blessings upon me. Life is good but even better when you experience it with fantastic people." Obviously Malik is Khloe's "us" and "fantastic people" reference, but maybe Lamar was included in that group???