Hi Michelle,
Im new to this forum and just signed up today! And while i dont know much about the forum one thing I do know a fair bit about is cocaine and alcohol.
I know its so cliche about its starts with a bit on the weekend and can escalate but it sounds like you are in that situation, using in times who swore you never would i.e ‘in the house’, carrying on and not knowing when to stop, finding it impossible to say no once you are a few drinks in.
I can tell you from first hand experience that it can creep into your life so fast that you dont even have to time to recognise the issue, as Dan says the best way is to really just cut those people out and even maybe cut the drink out for a while, focus on your relationship with your family. Take the £40 and go for a nice family meal, you can buy a voucher of Groupon for that price and have some quality family time!
Cocaine is a drug that really steals that time away and makes people very selfish! When you are using it you dont think of the consequences and very little else apart from the next line! It sounds like you know where your priorities should lie but once your having a drink in a social setting those lines get a little blurred.
It might even be a good idea to speak to these friends about how you feel, you never know they may feel exactly the same way!
Wish you all the best! You have a family and partner which is more than some! Be there for eachother and enjoy eachother you dont need that stuff in your life!