What does to be bitter mean?

[Holart]

English Grammar Tests, Elementary Level

ESL/EFL Test #132 "Conversations and Comprehension (3)", question 10

Woman: My sister was out of line yesterday. She really crossed the line this time.
Man: I know. She's really angry and bitter and she took it out on you.
Woman: Whatever the case may be, I don't think I want to see her again for awhile.
Narrator: What does the woman mean? .........

(a) She thinks that her sister behaved badly yesterday and she doesn't want to associate with her for some time.
(b) She thinks that her husband should excuse her sister's behavior because she is under a lot of stress.
(c) She thinks her sister's Internet system is down and that they should talk to her again when it's fixed.

English Grammar Tests, Elementary Level

ESL/EFL Test #132 "Conversations and Comprehension (3)", answer 10

Woman: My sister was out of line yesterday. She really crossed the line this time.
Man: I know. She's really angry and bitter and she took it out on you.
Woman: Whatever the case may be, I don't think I want to see her again for awhile.
Narrator: What does the woman mean? She thinks that her sister behaved badly yesterday and she doesn't want to associate with her for some time.

Correct answer: (a) She thinks that her sister behaved badly yesterday and she doesn't want to associate with her for some time.

Your answer was: correct
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what's mean to be bitter

[BrianL]

Curt; rude; short with someone; of a bad temperament.

It basically means she was being mean for no good reason.