Glad you posted about this. I smoked for longer than 16 years but I gave up in the summer of 2015. I no longer have any desire to smoke. So first, let me share a couple of thoughts which might add to your motivation.
Smoking is something only a few people do. Here in the UK, the smoking level is 19 percent but it's skewed heavily towards people who are uneducated and poor. Sorry to be blunt about it but that's how it is. I know you can find some examples of clever rich smokers but it still carries social stigma.
It's not just the cost of buying the cigarettes. It's the huge cost professionally that only now begins to sink in. In my professional environment smokers were never promoted. Rather than telling you why, I will let you ponder on the reasons for that.
The other you talk about is depression. Let me say that if you do quit smoking successfully and replace it with more rewarding things, it will give you a huge mood boost. It's not what you give up here that is important (the coughing, stigma and cost) but it's what you gain - a terrific sense of achievement. You can then go on and tackle other things in your life that you want to change, such as depression if that's an issue.
These are the two things I did to quit. I read Allen Carr's book The Easy Way To Give Up Smoking. I properly read it, making notes. I then went through the notes with a non smoking friend. I then read it again.
I told my doctor I wanted to quit (even though part of me didn't). I got an enormous amount of support and I found all kinds of tools are available for people who want to quit.
Today I worked out at the gym for an hour and didn't feel the slightest amount of breathing problem. I had my weight, blood pressure and cholestrol checked a year after quitting and I'm back in good shape.
You absoulutely can quit and you absolutely must. Posting here is a huge step in the right direction so I know you can take the next few fairly easy steps to get it out of your system. Trust me, once you're out of the trap you will rejoice and your mood will go up.