Sounds like a mean dude! The one used in gardens here does not, to my knowledge, have spines. It produces droopy large flower clusters, usually in dark reds. One of its common names is Love Lies Bleeding. The leaves are sometimes plain green or mottled red or pink and green. The plant grows to three or four feet in height. It is an annual in our cold climate.
Perhaps one way you could get at your plants to remove them would be to use a brush knife to cut it low to the ground, then dig up the remains. I don’t know how far down the pines go, but that might work.
If it is legal to burn garbage you could burn the remains of the plants that you cut, then have a controlled burn over the stubble.
I guess it depends on how annoying it is invading your garden.