I don't have a professional opinion but I'll try my best. If you're not in therapy right now then I would recommend it. It seems you have a lot of confusing memories of abuse to recover from.
From what I understand, it seems that you're confused if your mother's abuse was real or just in dreams you have had? If it has only been in dreams then I believe you're experiencing a confusion between "sex" and "love". When growing up your mother was never there for you. Never showing love, support, encouragement, etc. You yearned for that as a kid and dreamed for that intimacy. Instead of it taking the form of hugging or support though it took the form of sex. Being abused by your father probably didn't help the confusion either.
I know when I was abused since then I've confused sex and love. I desperately yearned for the support and love of my father and never getting it I would have sex with older men trying to seek that. Trying to receive that protection and support through sex. Anyways, it doesn't work. So I think with the case of your mother it may be sort of similar. As a child though the only woman you knew maybe was your mother. She was suppose to be the symbol of love and support. So in not receiving that, your mind tried to seek it through sex instead.
Anyways, please don't take this as a professional opinion. I just noted some similarities in what we've both been through. Please though get counseling from somebody. You won't ever get a perfect counselor but just try to find someone that's right for you.
Sorry this is all hitting you so hard like this. It sounds like it's a really tough time for you right now. I'm glad to hear you have a therapist, and hope you can talk through some of this stuff with them. That's the way forward, I think - getting this stuff out on the table so you can start examining it. Good luck, man, and hang in there, you will make it.
Of course you're feeling scared, and in a round about way this is meant to console you, and in that feeling scared you are perfectly normal. You let the genie out of the bottle and there is no putting him back in - now you have to deal - that's scary! But you're not alone in this fight, Stephan, you have us to lean on and share with and you have a therapist that you trust - you'll get through this.
I've been there and done that and, no, I didn't like any better than you do right now. And I didn't find it easy either. What I did find, however, is that it is do-able. One small step at a time as I felt able to take them.
I think that you need to give yourself more credit than you are. You are finally strong enough to reveal publicly the things that you did. It only feels scray right now because it is so new and you need to give yourself time acclime to the idea. Still and all, you've broken a barrier and that, my friend is progress in recovery!!!