<human>: I know this sounds a little stupid to not know if you cheated, but I think it is more a question of whether I should tell him what happened when I thought we were broken up. 

We have been together exclusively for a year and 5 months very happily except for some ups and downs regarding my sobriety. We are both in recovery and he has been sober 2 1/2 years where as I have struggled to maintain sobriety. The last time I relapsed he said it would be over if it happened again as he cannot have that in his life. I completely understood and felt he was very serious and even agreed.  

5 months goes by and I relapsed. After this he said it was over. I gave him back the key to his place, I didn't come over, we didn't talk much, etc... For a few days. 

Well, when I take the particular drug I was on, Xanax, I get pretty irrational and impulsive. This culminated in a meet with a man in which I gave him a blowjob. 

The next day what I thought was my ex started talking about missing me and when would I see him again. Before you know it he asked me to come over the next night and now we are back together. 

Reddit, I know what I did was inappropriate but I genuinely thought we were over. 

Is this cheating?  Do I have an obligation to tell him? 

I feel so guilty.

Can you give me the gist of the text in a nutshell?
<bot>: Boyfriend said we were over, I gave him back key and things, I gave another man a blowjob and the next day the boyfriend and I are back together. Is this cheating?  Do I need to tell him?