Necrophilism?!

Ch 16 "I shouldn't have discovered he had been there [at Cathy's coffin, in the great Drawing room, four days before she was buried], except for the disarrangement of the drapery around the corpse's face, and for observing on the floor a curl of light hair, fastened with a silver thread, which, on examination, I ascertained to have been taken from a locket hung round Cathrine's neck. Heathcliff had opened the trinket, and cast out its contents, replacing them by a black lock of his own. I twisted the two, and enclosed them together."

Ch 29 Heathcliff to Ellen: "'I'll tell you what I did yesterday! I got the sexton, who was digging Linton's grave, to remove the earth off her coffin lid, and I opened it. I thought, once, I would have stayed there: when I saw her face again--it is hers yet!--he had hard work to stir me; but he said it would change if the air blew on it, and so I struck one side of the coffin loose, and covered it up: not Linton's side, damn him! I wish he'd been soldered in lead. And I bribed the sexton to pull it away when I'm laid there, and slide mine out too; I'll have it made so: and then by the time Linton gets to us he'll not know which is which!'"

He then goes on to confess: "The day she was buried, there came a fall of snow. In the evening I went to the churchyard. It blew bleak as winter--all round was solitary. I didn't fear that her fool of a husband would wander up the glen so late; and no one else had business to bring them there. Being alone, and conscious two yards of loose earth was the sole barrier between us, I said to myself--"I'll have her in my arms again! If she be cold, I'll think it is this north wind that chills _me_; and if she be motionless, it is sleep." I got a spade from the tool-house, and began to delve with all my might--it scraped the coffin; I fell to work with my hands; the wood commenced cracking about the screws; I was on the point of attaining my object, when it seemed that I heard a sigh from some one above, close at the edge of the grave, and bending down. "If I can only get this off," I muttered, "I wish they may shovel in the earth over us both!" and I wrenched at it more desperately still. There was another sigh, close at my ear. I appeared to feel the warm breath of it displacing the sleet-laden wind. I knew no living thing in flesh and blood was by; but, as certainly as you perceive the approach to some substantial body in the dark, though it cannot be discerned, so certainly I felt that Cathy was there: not under me, but on the earth."

Ch 34. "We buried him, to the scandal of the whole neighbourhood, as he wished."

No, but he certainly seems to have lost the plot, so to speak, whilst scratching around her coffin, like some dog searching for a treasured bone.🐭

I thought he was having sex with her. He was kissing her and then he made an odd sound. I found this scene very confusing.