blackmailer: someone who extorts payment by threatening to disclose information that would bring disgrace or ruin (chantajista).
I don't mind telling you = I want to tell you: a relatively meaningless introductory phrase (déjeme decirle, permítame comentarle).
nerve‑racking: extremely trying to one's patience; causing irritation or exasperation (exasperante, que pone los pelos de punta).
smirking: smiling affectedly (mostrando una sonrisa falsa).
tending: looking after (cuidando).
spruce trees: coniferous trees (abetos, pinos).
study: a room in a house designed for studying, writing, reading, etc. (estudio, oficina privada).
drew up: composed or drafted in proper‑form (redactó).
will: the legal statement of a person's wishes concerning the disposal of his property after death (testamento). .
his brother in Alaska as sole‑heir: By placing the peak of stress and intonation on Alaska rather than on sole heir, the speaker implies that sole heir is an old idea and that the brother in Alaska is the new, contrastive element. We can assume, therefore, that Thomas Hunt was previously the sole heir. (su hermano de Alaska como único heredero).
You believed him? = Do you mean to tell me that you believed him?: a yes‑no question formed by rising intonation only, without inversion of subject and verb. It may indicate a certain skepticism on DeLator's part (¿Y usted le creyó?).

thunderbolt: a discharge of lightning accompanied by thunder (rayo, centella).
quarreled: had angry disputes (discutido, peleado).
cut me off: disinherit me; deprive the of the right to inherit(separado, dejado fuera, eliminado)
felt sure: was certain (estaba seguro, comvencido)
a good deal: much (mucho).
asking: asking me to pay him (pidiéndome que le pagara).
the executed will: the valid, existing will. Notice the contrastive stress on executed. The stress is shifted from the noun will (here an "old" element) onto the new or contrastive feature (la ejecución del testamento)
I refused to be blackmailed: Notice the peak of stress and intonation on refused rather than later in the sentence, because to be blackmailed is an "old" idea (me negué a ser chantajeado)
bargain = negotiate (negociar).
You can bet: You can be sure. Notice the stress and intonation peak on bet (same reason as previous note) (puedes estar seguro, puedes apostarle)
kicked him out: (colloquial) got rid of him; dismissed him (me lo saqué de encima)
Imagine!: an expression of disgust, surprise, or incredulity (¡imagínate!).
peddle: metaphorically, to try to convince that something is true (hacerme creer).
blunder: an embarrassing mistake (un gran error)