DD2 (32 months) is essentially weaned, though she's nursed at least once since the last time I said that. I cut back to only at nap and bed time sometime in the first trimester. Then we cut out naps, which went rather smoothly because she generally falls asleep in the car at nap time on the drive home from our outings. It does mean that we will do car rides at nap time if we're just home (I get myself a coffee on these drives ), but overall that was a pretty smooth easy transition.
I haven't officially cut her off from bedtime, but she's really not doing it anymore. She now asks to snuggle or walk with Daddy instead of rock with Mommy. I feel like that's a good transition for all of us to make before #3 arrives. DD1 was used to having DH to herself at bedtime, so it's a transition for her too. We give her the choice each night. I do love snuggling and rocking her.
Nursing HURTS like you describe, but the entire time she's latched on, and a follow up latch is absolutely horrid. I grit my teeth and watch the clock, telling myself I'll make it 5 minutes. I was making it less and less time. I wasn't telling her it hurt, though I did talk to her about her teeth hurting me and tried to work with her on her latch. I think her latch got worse as my supply tanked, and she was leaving tooth marks on me. I told her that my more sensitive side was empty (which it is, but I was telling her no about that side) because she drank the milk all up. She favored the other side anyway. I would tell her "I'm going to count to 5, and when I get to 5 you're going to be all done nursing, close your eyes, and go to sleep" and then I would count. I said it all in a very calm slow manner, and used the exact same phrase each night. I'd already established counting to 5 to stop pretty early in the pregnancy. DD2 still calls my breasts "my milkies". She really likes to put her hands on them, which absolutely makes my skin crawl, and I will ask her to stop, gently pulling her hands out of my shirt. She also likes to pretend to nurse, making a sucking sound with her mouth close to my (fully clothed) breasts. It makes me want to throw her across the room. I usually put her down when she does it. Not violent, not yelling, just telling her mommy doesn't like that and putting her down. My impression is she's doing it to be silly, as she giggles about it. She's very into pretending, especially about eating and drinking. I don't think it's an emotional missing it thing.
I think the weaning has generally been good for our relationship at this point. I too was getting increasingly irritated with nursing and with her in general (in case you can't tell that from the rest of this post).
Sending good vibes to you and your little one as you work through this.