As well as being a way of greeting someone you haven't seen for a long time, 久ひさしぶり is used to emphasize a long period of time that has separated two similar events.
It is often found in this structure, used as an adverb.
This expression is in most cases interchangeable with 久々ひさびさに.

Now, if you had a good textbook or a good teacher, they might have taught you that, on top of the correct sentence patterns mentioned above, "久ひさしぶりに" cannot be used with a negative form.
Sentences such as 久ひさしぶりに会あってない are therefore not correct.
In fact, Not being able to use the "negative form" is not exclusive to "久しぶり" but applies to any "~ぶりに" that is used in the context of "for the first time in [period]."

久ひさしぶりに is therefore used to express something that has happened, or will happen when it hasn't happened for a long time, and is always used with a verb conjugated in the affirmative form. 

Don't be tempted to use 〜ぶりに when you want  to express the notion of "not having done something in a while" !
Instead, here are several options where the interval of "not having done something" increases as you go down the list:

1. 最近さいきん○○(を)していない.
2. 暫しばらく○○(を)していない.
3. 久ひさしく○○(を)していない.
4. 長ながい事こと○○(を)していない.
5. 長ながい間あいだ○○(を)していない.
6. ずっと○○(を)していない.

Notes :
・The expressions 3. and 4. are a little more formal and will be used more in writing.
・It's common to add the adverb 全然ぜんぜん to emphasize the long duration.
・With the exception of 1. which simply means "recently", all these expressions are not limited only to the structure "it's been a long time since I haven't", but can also be used to refer to the fact that something has lasted, or will last a long time. 

To sum up:

It's important to distinguish when the action has actually taken place and and when it didn't yet. In the first case, use 久ひさしぶりに or 久々ひさびさに with the verb always in the affirmative form. In the second case, you'll need to use the expressions seen above with a negation.