Older men with no future!

I have been dating a guy for almost a year now. At first he was fun and exciting to be around. He loved my kids and my kids loved him back. Recently, he came over high (this has never happened before). He was not himself and he was so hi that he doesn't remember anything that night. Realizing the situation, I allowed him to spend the night. I watched him like a hawk that night not know what his actions might be. I realized that he was too high to drive anywhere else too! A few days later after he officially came off of his high, I let his family know of what had happened. They already figured that had happened but needed confirmation. Ever since he has been nothing but rude to my kids, he doesn't want to do anything but sleep and watch TV at my house. I feel like he has turned into my ex husband. Last night I tried to cuddle with him and he pushed me away. I want to leave him. I know from past experience that it only goes south from here. My only dilemma is knowing how and when to do it. I know that the rules have changed in dating, which is why I question it so much. Why am so stupid! Why am I so desperate for love and attention? Why is it so hard to love myself? Why do I feel so lonely all the time?