Okay then maybe forget about the show. Consider only the book please, what do you think of Claudia's ghost and diaries in the book? Did she hate Louis? Was that the real Claudia? And am I misremembering this part but did Louis kill himself because of what Claudia said or because of the Merrick heartbreak (I remember it was the latter) thank you for your time.
Well since I answered your first ask I decided to watch the TVL season of the show to see what everyone's shanking each other over so! I will probably have something to say later in my post-show debrief, but for now:
When I first read Merrick, I assumed that it wasn't really Claudia who Louis spoke to and I think I still stand by that after rereading it multiple times. For one thing, the "ghost" is much more dramatically cruel to him than Claudia was in her diary, to the point of cartoonish theatrics. The diary was seemingly very true to Claudia though, that she blamed Louis for her turning more than Lestat--and that she was very intentionally manipulating him for her own gain--but she's also honest about the fact that she loved him and never stopped loving him (or Lestat for that matter) in spite of her hatred for what they did. She couldn't forgive, but they were still her parents.
Her description of the afterlife as a vampire is very dark and hellish as well, and it seems to really contradict what we see in an objective manner when Baby Jenks is killed in QotD. They were both child vampires, and Claudia was especially young and innocent when her human life was taken. If Baby Jenks went into heavenly light as a teenager, I think Claudia did too.
It's also hard for me to imagine that Anne Rice would condemn the character who represented her own dead child to eternal torment and hatred. Instead, it sounds exactly like what some sort of demonic entity would say to torment a grieving, guilty father, exactly what Louis would be most afraid of hearing and already feared was true--that his daughter was suffering forever in the afterlife, that it was his fault, that he would never be reunited with her, and that she felt he deserved death too.
In addition, the ritual to summon Claudia's spirit isn't done correctly, they take a shortcut and use Louis' blood when the spell requires a human sacrifice. Merrick was able to summon her dead sister with her own blood, but she was also a human. Louis isn't. My reading is that whatever came forward using the vampire blood was some kind of evil spirit that simply wanted to cause harm and was successful. I even feel like Anne Rice wanted to make that distinction/mistake clear so we would doubt the validity of the apparition.
I think Louis' suicide attempt was about a lot of things, the apparition confirming his worst fears being one of them. The aftermath of Merrick's mind control and vampiric rape of him (along with the violation of the coerced romantic relationship itself) being another. Also the situation with Lestat's coma had been going on for like ten years by that point, so Louis probably assumed this was permanent and he was going to be alone and without the person who literally made him want to be alive. And being stuck with David Talbot, that could push anyone over the edge.