I gave up smoking after promising my stepdaughter to give up two years ago. Nowadays, I am find myself distraught and I am tempted to go back to my weekly cigar or pipe. Before I pick up my cigar, I would like to know should I take Kafara or do I have to do Istighfar to seek forgiveness from Allah as I find it very difficult to stick to the promise?
It is an act of hypocrisy to break a promise according to the Hadith. You have done a great job so far to overcome your desires as it is very difficult to control such desires in the first place. I advice you to please try again to control this and doing Istighfar is enough as this is an example of the continuous combat between evil and good.
Allah knows best
Imam Amjad Aziz Al-Azhari