I'm glad that you're self aware that you overstepped your boundaries with Sam. It's valid that you needed to talk to someone urgently. But one person can't be everything to you and your healing.

It's like how my best friend leaned on me with his OCD intrusive thoughts. I love him and I wanted to help him, and so for over a year, every day, multiple times a day, I would drop everything to reassure him about his OCD, talk him down from suicidality etc, and at a certain point it really started negatively affecting my life and I had to say to him "I can't keep going over the same conversation we've had a hundred times or more, you need to talk to a therapist, I'm still here for you but I can't be your therapist and talk about this every day". Fortunately my bestie honoured my boundaries.