You're welcome! I am happy to help you with any question you have.
By withholding sex, your boyfriend can accomplish two things- he can control you and he can make you feel bad about yourself, leading to further control of you. The lower your self esteem, the more control he feels he has.
He loves it when you show need because it lets him know that his tactics are working. He wants to be the center of attention and he wants to be needed and adored. To have you need him and be focused on him feeds his ego. He knows you feel worse about yourself and blame yourself when he withholds sex, so he will keep the game up so he can feel good about himself. This is all about him and not about you, except that he is using you to get his ego boosted.
The key to this is to show you don't care. Stop giving him a reaction and act like it's no big deal. This forces you to hide how you really feel, which is common in relationships involving someone with a personality disorder, but it also turns the tables and makes him react instead of you. It takes out the reward he gets when you react to him withholding sex.
He is also cheating on you, which makes it easier for him to withhold sex. His need to be with you will not be as strong as your need to be with him since you are faithful to him and you are not getting your sexual needs met elsewhere. So he is using that fact to control you and manipulate you.
The fact that he refused to discuss the broken windshield with you is another way to say he is not to blame for his behavior. If you did the same thing, however, you would be completely at fault because you are worthy of blame. But he cannot accept blame because if he did that, he would have to feel shame and that is an unacceptable emotion for someone who needs to feel he is important.