Black triangle w/red & green flashing lights, above air traffic lanes, hovering then EXTREMELY fast drop to very low altitude

I have a Celestron telescope with which I can see the moons of Jupiter, so it has very good clarity. I was out walking, and saw a black triangle with 2 red and 2 green flashing lights hovering over the area of the 29Palms Marine Base, and thought it to be a vertical landing F35 or other fighter aircraft. I ran inside my home, got the telescope, and focused it... other neighbors out walking had seen the craft and grown concerned as well. The lights were VERY bright, brighter than any drone lights I've ever seen, and brighter than any lights I've seen on an aircraft, and I've lived near airports and flight paths my entire life. The triangle was hovering above the airspace that airplanes use when coming in for a landing at the local Palm Springs Airport, and appeared to be about 15-20,000 feet in altitude. After hovering for about 10 minutes, a commercial airplane came into the normal landing pattern for the Palm Springs airport and passed by the object with what looked like several miles of distance between them, and about 20 seconds later the triangle abruptly dropped at an extremely fast speed, almost to the ground (it was no longer visible to me as a house was in the way). My spouse and several shocked neighbors saw it too. I then went back inside and Googled every drone and jet fighter VTOL picture and video I could find, and even thought it may be an Osprey aircraft, but nothing looks like what I saw.
For background, my spouse and I both have 20/10 vision, and are very skeptical about UFO sightings. But this was absolutely terrifying. We've never seen anything like this. Please do not release my name -- I don't want anyone outside of NUFORC contacting me or my family.