Rochester’s sudden swing to love is expressed through his regrets. He wishes he hadn’t spoilt their chances to love. He acknowledges his mistake.

“Everything false” (l.6), the faith he had put in Daniel Cosway’s accusations was shaken.
“Only the magic… are true” (l.7).

He says he has found the secret of love at Granbois.
He mentally addresses Antoinette.
He calls her Antoinetta, not Bertha or even Antoinette. He claims he understands her now: “I can hear you” (l.11).
He invites her to give herself up entirely to him (l.16).
This contradicts what he said a short time before. He admits he “made a terrible mistake” (l.17) considering her a mad girl.

But at the very moment when he is ready to admit his mistake he relapses into hate when he meets her own hatred in her eyes (l.18).

From line 18 on words, he seems to stubbornly against her and his happiness.
“In a sickening swing back to hate” (l.19).

He is bent on spoiling everything between them.
His hatred springs from her, but he is unable to compromise on yield.

He remembers all the poor reasons:

• Daniel Cosway’s letter: “it’s lies she tell you”;
• The arranged marriage: “they bought me…”;
• The so-called poisoning: “you betrayed me”:

The magic he mentioned moments before is “false” again: “no more damned magic” (l.23).

His attitude is rather childish, even masochistic.
“We’ll see who hates best.”
“ If I was bound for hell let it be hell” (l.23).

He destroys hope itself: “nothing left but hopelessness” (l.27), it is nihilism.

He concludes his hating spell wishing she would die. He even seems to be close to the edge of murder (l.29-30).

At that point, we may wonder who is madder: Rochester or Antoinette.

Then, as suddenly as he’d fallen into it, he recovers from his fit of madness.
“And that was all” (l.31).

After a climax/speak of hatred, an anticlimax of indifference appears.

There is no transition: he looks as if he were suddenly exhausted by his excessive hatred.
“All the mad conflicting, emotions… Sane” (l.36).
“No more love, no more hatred, only weariness and indifference”.

He now acknowledges, he was “insane” just a moment ago.
Now, he feels “sane”, i.e. he is not a within of extreme feelings.

No more destructive or self-destructive impulses. He again admits he loved her once and might have loved her better and longer (l.42).

But there’s no going back now.
The environment at Granbois looks repulsive again because it is a reminder of his failure with Antoinette.

He now considers her a zombie.
“She’ll join the others who know the secret” (obeah, voodoo, life and death).
He regards her as a living dead.

“A zombie to be watched locked away” (l.47-51) which is what he is going to do eventually because she is a dangerous lunatic, or so he thinks. She might “try to kill” (l.49), and she actually will herald the 3rd part in Rochester’s English country.

His last remark about giving Antoinette her money back sounds desperate. “What’s the use?” implies Antoinette wouldn’t be mentally capable of using her money.
Antoinette is definitively mad and must be locked.

Rochester’s constant “swinging” from one frame of mind to another quite opposite border on schizophrenia.

Schizophrenia: ambivalent mindset, paradoxical attitude.