What's the language of the NFA?
I tried expanding my comment to a proper answer. It was easier for me to write down the automata and the whole transformation process rather than using some software to generate it, thus I hope my handwriting is legible enough ;) (elsewise let me know)



The resulting Regular Expression is $[[b^*ba^*b]^*\cup[b^*aa^*ab^*b]^*]^*$

So the language accepted by your NFA ought to be something of the form $L = \{((b^lba^hb)^*(b^iba^jab^kb)^*)^*|i,j,k,l,h\ge 0\}^*$ (I've given a quasi-final form of the language).

The opposite of this language is $\sim L = \mathtt{REG} - L$

PS: Fortunately, a kind sir named Hendrik Jan observed that my conversion omits the fact that 2 is also a starting point. The solution is still holds for starting point 1. Now that you got an idea about NFA to REG conversions, I'll leave the REG determined by starting point 2 to you. :)