Pre kids i had a bit of a 'habit' wasnt just coke, E's too, sometimes base, the odd bit of hash for comedowns. I held down a decent full time job, committed relatioship, and a packed social life. One weekend we got through 80 pills in an all weekended. We often did half an ounce a week. We bought in bulk to save a bit of cash but would spend 200-300 a week on drugs. It wasnt a big deal to us, we knew the risks, we much prefered drugs to drink, we only had ourselves to be answerable to. You dont realise how addicted you are until its too late. at first you're not really addicted to the druig itself, more the socialising, then you become addicted to only being able to socialise with the drug, then you start doing it on your own, or in a couple, then you pop back from work on your lunch break to have a gram to steady your nerves before a meeting.....then you realise you've gone to far..... then you cant get off the bloody stuff!
I was quite lucky in that my DH wasnt as into it as i was, so it was easy enough to break away from the crowd for a while to stop, we actually moved country for a bit, that gave us break we needed to take stock, start our family, move back to a normal life. We have the same friends as we did then, some of them still use on a big night out, most dont bother anymore, the rest of life is too expensive to be able to afford it.
I also have a few mental health ishoos, the comedowns will get worse, much worse, you'll need more and more to get an equal high to the last one.. Then you will need even more than that as you dont want to equal the last high, you want to double it! Then the comedowns get even worse so you take a little bit the day after to ward it off a bit, then .....well you can see how it snowballs. But i do have an addcitive personality, i have friends who will have the odd line here and there now and again....you dont strike me as that kind of user though. You sound more like i used to.
Sorry this is long, i didnt want to just pass judgement, I have been there, without the trainspotting lifestyle, owend my own home had a good job, studying....it will snowball and you wont be able to stop it. The odd gram now, not so big a deal, the odd ounce in a months time....well can you afford £1k a month? best start saving if not and you want to carry on :)