Thank you all for your replies. They have been very helpful during this time.
He has managed to stay sober for the last 48 hours (I.e. since the relapse on Friday night) and has been going to meetings. I think what is hard right now is that I'm still processing it and feeling hurt, but he just wants to move on and start over.
I guess what is worrying me the most is the future. We don't have children yet but before this happened we had chosen a ring and were planning to get engaged and married soon. That is something I need to put on hold. I love him so much but this stuff is really scary and I don't know if I can take it on.
I think I'm only now understanding what it means to be dating someone in recovery. I guess I have been pretending it didn't exist but this brought me to reality hard. I think it's probably unrealistic to think he will never slip up again, but I think our future will depend on what that slip up turns into. If it is just one episode and then he turns it around and gets his sobriety back on track right away then it's something I can probably handle. But if one night of smoking becomes 2 becomes 3 etc it will be too much. I also think it depends on how often it happens. I'm just conflicted and confused right now and so unbelievably drained. I had lots of other obligations this weekend and it was so difficult being away from him and pretending everything was ok. I just am so tired and feel like crying with every breath. I just keep picturing him on the toilet w his shorts around his ankles, pipe in his hand and frantically going through all his stuff to try to find more. I know I asked him to let me in but I'm so disturbed by it. That's not the man I love and want to marry. I didn't know who that person was.
I'm going to go to an al anon meeting later even though I feel exhausted. I'm hoping that it will help.
Thanks again to all of you for sharing your stories and reaching out to me. I truly appreciate it.