[~invisible~girl~]

You should tell her. A lot of times people hide things from their therapists because they want their therapist to think well of them or want to be a "good patient," but it really just gets in the way of treatment, and no therapist worth trying to impress will think any less of you for being honest. Also, it's really common for SI to become a routine like you described, so it's nothing to be embarrassed about, and she's not going to think you're crazy. Your therapist can't help you with something she doesn't know about, so you'll get more out of therapy if you tell her more. It takes time to build trust with your therapist, and it's totally and completely normal to want to hide some things, but you should always try your best to be honest with her.

A good therapist won't think you're "crazy" no matter what you tell her (and a bad one isn't worth trying to impress anyway). A good therapist will probably understand why you feel the way you do, or at least recognize that there's a genuine and legitimate reason for it and accept it without judgement. She'll also understand about you being embarrassed to tell her, and about how hard it can be to feel like you have to keep it a secret. For a therapist to think their client is "crazy" makes about as much sense as for a medical doctor to look down on a patient because she's sick.