I am so very proud of you for messaging your friend. Well done for speaking the truth "out loud" and taking an important step to protect yourself and your children.
Let's say for argument's sake that we did not know about the rape that took place when you were heavily pregnant. If you described only what happened yesterday - that you had, more than once, prior to bedtime, been very clear with your husband that you did not want to have sex, that he had then attempted to initiate sexual contact once in bed and you had again said no, that you had then woken to the weight of a fully grown adult man on you as you lay face down in bed while he masturbated over you and that he had then asked if he could fuck you - those things by themselves are plenty for last night to be another assault. You told him no several times. He only asked you when he was already engaged in a sexual act that had started while you were sleeping, and only when he was physically restraining you with his body weight.
I also wanted to warn you that I think it is unlikely he will not assault you tonight. He is creating a narrative in his own head that you are initiating the sexual contact which is clearly bollocks but I suspect him telling you that's he's not up for it tonight is another mind game and you may very well find that he rapes you again before tomorrow. I'm sorry if I sound very dispassionate about it, this is like how it was with my colleague and I am trying to remain very factual and warn you, I don't want you to have a false sense of security.
If he starts/threatens to physically harm you to the point you are frightened for your life then I would tell him that you have disclosed to your friend already and that he needs to stop right now as no one will believe that he didn't mean to hurt you. For my colleague, the rapes increased in frequency and severity physically until one night he restrained her by the neck (the single biggest predictor that a man will go on to kill you). She left the next day.