hey,i think you should atleast wait till your exams get over....itz not really that long away so im sure you cud wait a while longer.if u tell her now itself,it mite affect ur perfromance as well as herz(whether her reply is positive or negative)
so for now,stop worrying about it and sit for ur exams with a cool head.but once ur exams are over,therz no getting away from it.....u hafta tell her,man.
there are 3 possible scenarios:
1.she cud say yes
2.she mite play a lil hard to get(think of it as sweet revenge..we girls are like that

) but she eventually will say yes..she jus needs you to persuade her and convince her about your love
3.she jus might say no...bcoz the past is past and she mite have completely gotten over you n now thinks of u as nothing more than a friend...
i hope scenario 3 dusnt happen but even if it does,dont lose hope...keep trying and she'll be yours!!
oh...and please do cut down on the cigs...itz not helping you n i dont think shed b too pleased if she knows about it.
all the best.do let us know wat happens after u tell her
C Ya