"She was the brightest light, a magnetic force of nature and was loved by so so many," the post read.
The Santa Barbara County Sheriff’s Office identified MacMillan as the woman who was hit and killed by a train on Monday, per KEYT. Two days prior, police were asking for the public's help in finding MacMillan, who was reported missing after she left her "car, wallet, keys, ID and cell phone" at her Santa Barbara home. According to the police report, authorities feared she may have been suicidal.
"If we can do one thing for Lee now, in the midst of this soul-crushing loss, it's to spread the message that mental health is just as real as physical health, and that illness can strike anyone, no matter how unlikely they may seem," the post continued. "It's ok to not be ok, it's ok to ask for help, it's absolutely necessary to ask for help."
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The message added that MacMillan was "not alone" in her fight, as she was "receiving help" from professionals, family and friends.
"And yet she still succumbed to this terrible illness. It is more nuanced than we can, or do, appreciate or understand."
In December, MacMillan shared a 15-minute video on Instagram where she detailed her mental health battle and opened up about her suicidal thoughts.
"A huge thank you to all of the people in my life who continue to lift me up," she captioned the clip. "I appreciate you."
If you or someone you know is struggling with depression or has had thoughts of harming themselves or taking their own life, get help. The National Suicide Prevention Lifeline (1-800-273-8255) provides 24/7, free, confidential support for people in distress.