Oh that's nothing. At least mating in copepods still doesn't hurt.
Try some insects, where the males actually drill a hole into the females abdomen while holding her down and injects his sperm into the hole.
Bedbugs being the most common example. A war of the sexes, where females have all evolved to defend themselves against males, and males have all evolved to attack females in order to reproduce. Yes there is no vagina. And yes some females die from the injury, and in cases where the male rapes a female of the wrong species, he usually kills her. A species of rapists.
Or how anglerfish males who become living sperm dispensers attached to the female body for the rest of their lives. Or barnacles with the longest penises several times as long as their body length in order to be able to mate with nearby females (they're sessile). Or porcupines who engage in golden showers... LOL and worse... Hippopotamus males who spray shit and urine at a prospective female hippo so she'll agree to mate with him. ROFL
Animal sex is weird.