You know, a popular phrase with recovery and things like that is often "Rome wasn't built in a day." Okay, so I don't know if what you are doing is necessarily "recovery" per se. I guess, maybe, if you felt you had an addiction to that release then maybe it is. But, whether it is or not, I think it applies here.
You had a slip up. That is a shame.... but you are human. It happens. Don't beat yourself up too much. Nothing wrong with trying to do better, striving to get to the point where you don't lapse. ....but at the same time, look how well you were doing. Slip ups may happen from time to time. In time, hopefully you can and will get to the point where it is within your control. Whether that means never doing that at all, or whether it means only doing it here and there in such a way where you don't feel bad about it. Whatever that means for you, hopefully you ultimately achieve that.
But, don't let one slip up, or even a slip up here and there, bring you down too much. As long as you do your very best not to make it a slippery slope where all your progress is lost. Even the best of us has a bad moment now and then.
As for the teddy bear you mentioned, the one that you connect to your ex... It can be hard to completely let go of a relationship that, at one time, you maybe thought could be something really special. Especially in a case like yours where she was the first person you ever really went all the way into a serious relationship with in your life. You will eventually reach a time when you realize she is in your past for good and realize that you are actually probably better off that she is. Maybe you'll then be able to get rid of the teddy bear, or maybe you'll decide to keep it around but it will no longer have the same negative influence on you.
Life is often a series of ups and downs. It might be nice if things could always be amazing and awesome. But, that just isn't life. Unfortunately, the bad times, the tough times will always come around. But that doesn't mean it ISN'T worth fighting through them and back to the good times. Heck, quite the contrary. That is all the more reason it IS worth fighting through the bad times and back to the good times.
Anyway, you can do it, PC. You were doing so well. Don't let one tiny slip up set you back. You can do it!