Yeah, old wounds can definitely come up in EMDR, and it can take a few weeks to re-process it all. In the mean time, everything can be upsetting.

I don't like that your therapist was insisting that you dissociated about something happening with your mom. I'm not a professional, but that sounds unethical to me.

Trauma can create emotional parts that are split off from the rest of your personality, and those parts can be frozen at the age when the trauma happened. Your brain quarantines the area to help you survive until it's safe enough to process it. So, if you were working through a trauma that happened when you were very young, it's understandable that you could briefly experience a moment where you were experiencing the part of yourself that was split off at the young age, before you had developed the resentment.

That's exactly what's supposed to happen. Healing from trauma means re-integrating those split-off emotional parts.

I have had buried memories come up, too. It's unlikely that you are creating false memories of abuse, because the last thing anyone wants to believe is that our parents abused us. That's why we shut out the memories in the first place. We do everything to bury it, because there is a lot of pressure from society to respect your parents at all costs.

Yes, incestual grooming can absolutely create a fear of intimacy, which would cause you to push people away. I can relate to that. Before you integrate those experiences, you can get thrown into the split-off emotional terror of desperately rejecting your mother's sexual advances. And then, of course, you might sabotage the relationship or vicariously seek revenge against your mother by using your partner as a proxy.