Help explain と in this sentence [duplicate]

Question

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• Am I understanding this correctly? しないと 1 answer
• Differences between 'must' 1 answer
• What is と in this sentence? 2 answers
• 少しぐらいは and 少しぐらい usage in casual speech 2 answers

私も行かないと。

I understood it as "I also won't go." But according to Tae Kim's guide and Google Translate it is read as "I have to go too." Why is that? I assume と has something to do with it since removing it gives me what I understood of it in the first place or so sayeth Google Translate.

For the full context:

Ａ：行かなくてもいいよ。

Ｂ：だって、みんな行くって。私も行かないと。

Yeah. What I understood of it does not make sense in this context.

Answer 1

In this context, I would interperet といけない to mean "I must" (because there is something you must do elsewhere etc or you have some obligation to fulfil).

So: 私も行かないと = I must also go.

私も行かないと is actually a contraction of 私も行かないといけない or 私も行かないといけません.

For example:

私も戻らないと → 私も戻らないといけません

Tae-Kim explains it here (better than me!): http://www.guidetojapanese.org/learn/grammar/must