I read this book once as a teenager, I think it might have been written in the 1970s but could be late 1960s or early 1980s.
The protagonist is left to die hideously by enemies. He is paralysed and left on some planet (I don't believe it was earth) in the habitat of some kind of crablike creature, which injects him with its young, and periodically returns to force nutrient and a paralytic agent down his throat, as the larvae grows inside him.
He is rescued, and his body rebuilt to some kind of superhuman abilities, but he is traumatised and bent on indiscriminate revenge for his suffering. He proves hard to defeat.
He is eventually defeated by trickery, when he is shown (or demands to see) something by some kind of video link or remote TV/monitor - perhaps he is told that people he wants revenge on, are held captive for him, I can't be sure.
I think maybe he takes hostages or makes a severe threat, and his demands relate to the people he wants revenge on. But he can't be physically reached, so what can be done? They set up a video feed, to negotiate, or more likely, to purportedly show him they have what (or who) he wants, and he looks to see.
When he looks at the video stream, it's actually an image of the crablike creature. The shock of repressed memories flooding back, renders him re-traumatised and perhaps catatonic, and defeats him.