Hello Meerkat 80, and a warm welcome to the site.
It's easy to hide our depression, simply because we don't want to have to explain to people why we feel this way, or for them to argue why we shouldn't feel this way because everything seems to be going along adequately, but in fact, you're not, you are suffering, unfortunately.
Mental abuse is not what anyone wants and sometimes smoking is a way for people to take their mind off the situation, and I'm not making a judgement on this, it's something you decided on doing under the circumstances.
The thought of stopping may not have entered your mind until you feel as though there is help to direct you in another way, maybe one you might not have considered before, simply because you weren't able to.
Sophie_M has provided you with some great links and perhaps RESPECT 1800 737 732 may be able to guide you in a positive way.
We'd love to hear bac from you whenever you're available.