Love isn’t always wise. I’m sorry you are in such a painful situation. I’m sure it feels both scary and terrible to realize this man isn’t who you thought he was. But let’s be honest. He has not been a great dad to your daughter. He is not loving her mother. He is not committed to making the kind of family she needs to grow strong. He is not committed to putting his responsibilities as a father above his desires to be a man about town. He’s lying. You’ve let the situation turn you into a snoop.
You and your daughter deserve better. Your boyfriend may be able to avoid growing up but you can’t. You may be only 20 but you have a daughter to raise now. Give up on trying to reform this guy and start focusing on what you need to do to make the kind of home you and your daughter need. Give back the ring and let your “fiance” know that until he is willing to grow up, get married, and help support his family, you’re not interested. Get a lawyer and find out what your rights are regarding chld support. Make sure that visitations with him are safe for your little girl.
When you’ve stabilized your home, you can think about finding someone to love. I’m sure there is a good man out there who will love, cherish, and help provide for you and your little girl. Don’t accept anything less.
I wish you well.