Ashley Tisdale — Fan Tweets Actress 18,000 Times … Cops Investigating

Exclusive 0513_ashley_tisdale_gettyAshley Tisdale“s legitimately freaked out … after an obsessed fan sent more than 18,000 tweets to the actress and then showed up to her home, our sources has learned.

Law enforcement tells us … the LAPD has launched an investigation after a person in Ashley”s camp reported that a super-fan had tweeted at her 18,888 times, dating back to November, 2012.

The tweets are pretty creepy — the person (believed to be a man) seems to be delusional, writing as if the two have some sort of ongoing relationship. For example:

“My body is yours & even as friends I f***in love how I make u feel like mom maybe we both got issues cuz nobody”s perfect.”

“I”ll never lose u baby even in 20 years til infinity you”ll always b my best friend.”

“Let it all out on me u can have my heart put a lock on it throw away the key & my soul is yours to keep.”

Even scarier … we”re told the suspected super tweeter recently showed up to Ashley”s house … but we don”t know if he ever made contact.

We”re told cops have identified a suspect — and are looking to talk to the person to determine whether he poses a serious risk to Ashley.

Calls to Ashley”s reps have not been returned.