A movie seen in the early 90’s on tv. Pretty sure it was from the early 90’s, if anything, the late 80’s.
There was a scene where a woman was pinning a girl down in a full mount and holding down her arms. They’re in the backyard of a house and it’s brightly lit from the lights and the pools lanterns. Then a closeup of the woman’s chest shows something crawling up from the inside. From her mouth, a centipede-looking thing comes out of her mouth and she tries to pass it into the girl’s mouth.
Two people then run out, a girl (mother? sister? cousin? friend?) and a guy. They knock her into the pool and the guy chucks a propane tank in, too. He shoots the tank with a gun and it explodes, killing her.
There was also an earlier scene in which someone was pointing a gun at the woman and she dared them to shoot her. When they shot her in the head, she just leaned back and raised her head back up with a new bullet wound.