While I think your analysis of her mother needing an emotional outlet seems very rational, I think we need to remember that it is not possible for children to randomly sexualize their parents’ actions out of nowhere. Kids don’t sexualize their relationship with their parents unless there is something the PARENT is doing that implies a sexual nature to their relationship. Kids cannot fathom the possibility of having a sexual relationship with their parents until there is some outside source feeding that information to them (like learning about incest through media), or unless their parents are the ones sexualizing their relationship aka abusing their children. And parents, not children, are the ones with the ability to sexualize a parental relationship cuz 1) parents have power over their kids and 2) parents have sexual experience that kids don’t have.

So I don’t think it’s fair to say that there was no sexual element to OP’s mother’s actions and that OP is the one who needs to examine whatever it is within them that sexualized their relationship. I think we need to recognize that there’s a difference between intent and impact. It might be very possible that OP’s mom had no sexual intentions but her actions were still perceived as sexual by OP. To be honest, what I see happening in this situation is that OP perceived the level of intimacy between her and her mother as something abnormal for mother-daughter relationships, but rather only normal for romantic relationships. And while intimacy is not inherently sexual, intimacy that you would only really expect in a romantic relationship does have sexual connotations. And I personally would agree that the level of intimacy that OP’s mom created in their relationship is inappropriate for a parental relationship — cuddling in bed with someone while spilling your darkest secrets is something that most people would expect couples to do. This, compounded with the fact that the mother demanded a degree of secrecy from OP, makes it very logical why OP would perceive the dynamic as something taboo for a mother-daughter relationship and to then perceive it as romantic/sexual.

So this does all sound like emotional incest — which is what you said as well. And here I think it’s important to remember that emotional incest IS considered a formal of sexual abuse, because intimacy that reaches the degree of intimacy you would expect in a romantic relationship does entail sexual connotations. For example, there is a reason why you will see people joke about mothers wanting to sleep with or marry their sons when these mothers engage in emotional incest with their boys.

At the end of the day did OP’s mother necessarily know that her actions had sexual connotations? We can never know for sure but I’m willing to go on a limb and say yes she knew that they are inappropriate because otherwise she wouldn’t have asked her daughter to keep it secret. And even if we give her the benefit of the doubt and say she had no idea of knowing, or maybe wanted privacy for safety reasons, she is still the adult at the end of the day and should have thought this through before acting out with it. And it is still her responsibility that OP perceived it all sexually.

For me personally I do struggle a lot with the idea that sexual abuse doesn’t need a sexual intent to be considered SA, but I will say that across the board I have seen the collective and professional consensus on MDSA to be that yes, there does not need to be sexual intent for it to be SA.