'Ich muss dich vergessen' means 'I must forget you.'
I haven't forgotten you.
"Ich werde dich fressen" means "I will eat you" in German.However, the verb fressen indicates that it is an animal that is doing the eating.
Ich werde Sie töten translates as I will kill you.
I think the person said, "Ich werde dich töten, Sie Hunden" which is grammatically incorrect, even if I rewrite it, because it would have to be, "Ich werde SIE töten, Sie Hunden" or "Ich werde dich töten, du Hund." The first one means "I will kill you (plural), you dogs" and the second one is the same but singular.
"This time I won't ever let you go."
I heard he has a British butler.
"Ich brauche dich" is "I need you" in English.
I will thank you for it.
werd' ich is an abbreviation of werde ich and translates as I will.
Ich werde Dich für immer lieben translates as I will love you forever.
Ci vediamo presto. Ich werde dich bald sehen.