<human>: My [23f] boyfriend [30m] tonight "wanted to be honest" and decided to inform me that he took a bump of coke when he went to go pick it up for his friend. 

Now I knew that he was picking it up, and he promised me that was all he was going to do...he  has had drug problems numerous times (more prescription stuff) in the past, and they took a terrible toll on our relationship, but i stood by him and helped him fight...or so i thought. We have been together for 4 years and sometimes I feel like he will never change.

Anytime a recreational drug is offered to him he seizes the chance to take it, i tried to talk him out of taking something once and he downright refused to listen to me. 

I have a very bad history with drugs, I have many family members who abused them, including one of my immediate family members and it absolutely killed me. I'm no saint, but I know when things are becoming an issue. I don't mind the lighter things and I tolerate his smoking habits, but he told me before he went to get it that "He would never do it" and when I asked him why after he goes "I had to" you know to make sure it was "good" for his friend. That seems like a bullshit cover for he wanted to. But why now? He will probably be drug tested soon for a new job and he knows my emotional issues with drugs, we have discussed them before and he has promised time and time again he will never abuse something again. 

I'm furious right now...I'm not sure what kind of advice I'm looking for...maybe someone with a similar issue? Thanks Reddit.

Can you summarize the given text in a few sentences?
<bot>: My [23f] boyfriend [30m] of 4 years keeps running in to drugs despite how I feel about them