This relationship is going nowhere. You don’t trust your boyfriend. He continues to give you reasons not to. He has an active fantasy life that goes beyond talk. He’s asking these women out to dinner and inviting them into your home.
You aren’t blameless. Your response to his behavior is to cheat to get even. Obviously, it doesn’t work. Of more concern, it shows you to be as immature as he is. You then fall for it when he cries and you let yourself get talked into trying again. What a painful and pointless cycle. He lies. You cheat. He cries. You give in. And the whole thing goes around again.
I suggest that you take responsibility for your part of this endless game and get out of it. Learn from your mistake. Make yourself available to someone who is ready and able to be in a committed relationship without all the drama.
I wish you well.