Trace Cyrus Accuses Brenda Song of Faking Pregnancy, Brain Tumor During Relationship

Trace Cyrus says Brenda Song brought her acting chops into their on-again, off-again romance ... accusing her of lying about some serious topics to him and his family.

The son of Billy Ray and Tish Cyrus took to his Instagram story to spill the alleged tea about his coupling with the former Disney star -- whom he dated intermittently from 2010 to 2017 -- claiming she concocted a series of elaborate lies.

According to Trace, Brenda stole thousands of dollars from him, faked multiple pregnancies, and even allegedly used fake blood to convince him and Tish she'd had an abortion.

However, Trace claims they took her to the OBGYN to make sure she was alright ... where he says they found out Brenda made both the pregnancy and abortion up.

On a different occasion, Trace alleges Brenda told his family she was terminally ill ... telling them she had breast cancer and a brain tumor -- before he says she claimed she went to Chicago to get the tumor removed.

Trace says the family was catching on to all of her alleged falsehoods ... and, he says he physically ripped the bandages off her head in order to show she had no scars underneath them.

Cyrus says this goes to show how much childhood fame can hurt the kids ... and, he says he hopes Brenda's doing better mentally.

Worth noting, Trace doesn't provide any evidence to support these allegations. Trace is also prone to outbursts on social media ... ripping his father as "delusional" and "evil" in an acerbic rant earlier this week.

Shortly after Trace and Brenda ended their relationships the last time, Song began dating Macaulay Culkin. The couple shares two kids -- one born in 2021 the other in 2022 -- together.