Tell your T. Tell your T everything. If we didn't have any cracks or if we'd fill all of them in perfectly--there'd be no job security for therapists.
It sounds as if you knew you were walking into a hot-issue situation and had some plans to help with that. The motel age thing threw things off, because you lacked a backup plan. And everything kind of got away from there.
It was a complicated situation from the git-go, you're 20, learn from this. It's precisely the sort of complicated situation with lots of possible ways of falling apart that have brought therapist and client together. You're a classic!!
Take notes.