The facts that are not in dispute appear to be as follows:
You were at home with your boyfriend and your 13-year-old daughter. You and your boyfriend were in a heated argument. He then hoisted you over his shoulder and carried you into the bedroom, closing the door. You started screaming and protesting. Your child believed you were being attacked, got your pepper spray, entered the bedroom and sprayed your boyfriend in the face. He then took the pepper spray from her and sprayed her in the face. Your daughter called 911.
Your version of what happened after you entered the bedroom appears to be as follows:
You like rough sex, and even though you had just been in an angry fight with your boyfriend you decided to switch gears from fighting to "making up" in a way that people unfamiliar with your preferences would confuse with fighting. Unfortunately you were so loud in your responses to your boyfriend that your child was confused and believed that he was attacking you, and entered to spray your boyfriend in the eyes with pepper spray. Your boyfriend grabbed the pepper spray and sprayed it on your child.
Even though your daughter had called 911, and you knew the police were coming, you got your children (the 13-year-old presumably being the oldest) together and went to your sister's house. Your reason for this was "to try to get the mace off of us both", although if cleaning your child's face and eyes were the issue it would have seemed much more sensible to do that at home rather than making the child wait.
The police then arrived at your sister's home, having found you there because... (you haven't explained). You then told the police that your daughter was mistaken about what had happened and, although you had been in a big fight with your boyfriend, he had hoisted you out of the room, and you made noises that made your child (or children) believe you were being hurt, once the bedroom door closed everything became consensual.
Now, for reasons you do not know and cannot explain, the police are falsely claiming that you accused your boyfriend of sexual assault, when you told them it was consensual rough sex. Your sister was sitting next to you when you made the report to the police, and she'll confirm that the police are simply making stuff up.
The police version of events appears to be as follows:
They received a 911 call indicating that a man was attacking his girlfriend and sprayed her child in the eyes with pepper spray when they tried to get him to stop. When they reported to the home they found signs of a disturbance, but that the alleged victim had left the scene with the children. (Perhaps the boyfriend was interrogated at this point; you haven't shared.) When the boyfriend was detained, he was found to be in the unlawful possession of controlled substances. They then (somehow) tracked you down to your sister's house where your daughter (or perhaps all of your children) confirmed the 911 report. They questioned you and you confirmed that he attempted to sexually assault you. They may also have noted that you refused a rape kit, and they suspected that you did not want your boyfriend prosecuted for any of his actions.
If I were a prosecutor reviewing the case I would see a statement from the child (or children) consistent with the police version of events. I would see physical evidence consistent with the police version of events. I would see a boyfriend who probably has a record, who was caught with illegal drugs, and who though it was appropriate to pepper spray a child in the eyes. And I would see you who, after reportedly giving a statement to the police that was consistent with that of your child(ren) and with the physical evidence, were stating that the police were lying in order to set up your boyfriend. I would know that the police have no reason to lie, and would be putting their careers at risk by lying. I would likely conclude that you were one of the many victims of domestic violence who, having made a truthful report of an incident of violence to the police, wanted to retract that report - but that you were afraid that if you scuttled the prosecution with an outright retraction, an "I lied", you might be prosecuted for filing a false police report.
And yes, as Dogmatique suggests, I would be concerned about whether you are looking out for the welfare of your children, whether you are going to put your children at risk by allowing this boyfriend to return to the home, and whether protective services should investigate the home (if they're not already).
Even if I assume that you're the one who's right and everybody else is wrong, I think that's how a prosecutor will perceive the events and story you've recited.