Peter Holm, locked in a bitter divorce battle with "Dynasty" star Joan Collins, barricaded himself yesterday in the house they once shared, vowing to shoot anyone who tries to evict him.

"I'm just not going to get out of the house without a proper court order," Holm said last night. "Anybody who tries to force entry here will be shot. There's going to be a battle here."

Armed guards hired by Collins were also reportedly patrolling the property to protect her interest.

Collins and her estranged husband have been in court several times in the last six months over use of the house.

Holm, who is seeking $80,000 a month in alimony payments from the actress, has a temporary restraining order allowing him to use the house until it is sold. The court on Dec. 22, 1986, ordered Holm, a onetime Swedish rock star, to vacate the house as soon as its sale is legally finalized.

Earlier yesterday, Collins' lawyer Marvin Mitchelson said he notified Holm's lawyer, Frank Steinschriber, that escrow had closed and Holm had until 6 p.m. to vacate.

However, Holm remained inside past the deadline and invited a handful of photographers and a television crew inside for a tour of the huge house, unfurnished except for his bed and a few paintings, including a large one of Collins.

Sen. Kennedy's Car Hit By Tree Bruises and cuts from a Wednesday night automobile crash were not enough to keep Sen. Edward Kennedy off the Senate floor yesterday. The Massachusetts Democrat sustained the minor injuries when the car in which he was a passenger was hit by a falling tree on the George Washington Memorial Parkway. Kennedy was on the way to his McLean home from a Senate session at the time of the accident. He was treated by congressional office physicians for minor leg and facial injuries. The driver of the car, Kennedy aide Michael Gavigan, was reported unharmed, but the car was damaged so badly it could not be driven.

Nancy Reagan to Attend Wedding First Lady Nancy Reagan will attend the wedding of her only niece, Anne Mumford Davis, in Maine tomorrow, her spokeswoman Elaine Crispen said yesterday. Davis, the daughter of Mrs. Reagan's stepbrother, neurosurgeon Richard Davis, is to marry Jon Milton Peterson of Fairfax, Crispen said. The couple became engaged at the White House last Christmas.

As one of several wedding gifts, the first lady plans to give Davis a bracelet once owned by the first lady's mother, Edith Luckett Davis, and grandmother, the late Sarah Whitlock Luckett. Crispen said Mrs. Reagan will travel to York Harbor, Maine, tomorrow morning and return to the White House later in the day.

Bloomin' Mad The National Federation for Decency is after "Bloom County's" Berke Breathed. Evidently, the federation's executive director, the Rev. Donald Wildmon of Tupelo, Miss., doesn't take too kindly to the Pulitzer Prize-winning cartoonist's creation of Edith Dreck.

Wildmon says the word "dreck" is the Yiddish term for excrement, and he has written to newspapers across the country, asking them to discontinue the strip, and to The Washington Post Writers Group, Breathed's syndicate, asking that the cartoonist be fired. But in a telephone interview with UPI Wednesday, Breathed said he doesn't know Yiddish and that Wildmon is "full of dreck" for raising the issue.

Steinem, in Style The August issue of Vanity Fair features feminist Gloria Steinem in a black leather miniskirt showing off her youthful legs. Hemlines are up this year and Steinem, 53, has a theory about the change. "Women have seized control of what they're wearing," she says. "It's more about style, less about fashion." But the change in styledoesn't affect Steinem, who says she's always favored short skirts. "I never stopped wearing them," she says, but acknowledges she wouldn't wear one to "a blizzard."

Chuck Conconi is on vacation.