It probably wouldn't be helpful to you and the therapeutic relationship if you avoid the subject; that's like sweeping it under the rug. That said, however, if you've been seeing this therapist for some time and came to trust her, it makes sense for you to want to avoid it out of fear that she would further invalidate you and your feelings. That would hurt even more than the first time she invalidated you. If I'm your situation, I'd choose to bring it up. Tell her that why this subject is important to you, and how her previous response made you feel. If she still doesn't get it, she's not worth your time or money.