I'm autistic so I don't know how to interpret her reaction either, but it still sounds very unprofessional and judgemental. What kind of therapist acts like that because of such a harmless confession, seriously ?
If she can't even deal with that, you don't want to trust her with your problems, OP.
I'd say, trust your gut feeling and get away. You might be tempted to continue seeing her to prove yourself to her but you'll regret it in the long term. A therapist told me "I've never seen anything like that before" in a condescending manner, yet I gave that cunt the benefit of the doubt and kept seeing her. It just got worse and to this day I still feel like a pathetic cuck for doubting myself. Most therapists are useless at best or fuckwads at worst, finding a good one is hard. Stop the damage now.
If you like her because she's motherly to you, maybe you have an issue with parental figures. There is an ex-therapist called Daniel Mackler who talks about parental and therapeutic abuse and how the two are linked, you might find interest in his youtube channel.
Also, I feel you. Being assertive and knowing when and how to stand up for yourself is tough for sure.