You and many others have fallen into the trap of a cheating partner. Can a cheater ever be forgiven? Yes. But not all of them. There is a book I would recommend to you called "After The Affair"by Janis A. Spring. The only person who can make the decision as to whether or not you two can work it out is you. Your trust has been betrayed.
If it is advice you want, I would tell you that you already have the answer right in front of you but it's too painful to see it. If he was already caught the day before your daughter was born and didn't stop cheating after she was born, what makes you think he's going to stop now?
You're right, your daughter is the most important thing and part of being a good parent is not subjecting your daughter to an unstable home environment with a father who cannot be faithful. A unified home is best, but with your situation, your relationship is hardly unified. Many women do it just fine on their own. Many of them go on to find wonderful husbands who end up being much better fathers to their children than the biological father.
Ask yourself what kind of man cheats on his pregnant fiance? If you take him back, I honestly believe you are only setting you and your daughter up for further hurt. Kids know when there isn't peace in the home. What you think is protecting her by staying with him is actually only endangering her emotionally later on. Kids in 2 parent homes where the parents fight all the time are more dysfunctional than children in single parent homes where the parent is stable and happy.
I know it's painful and you probably feel very alone right now. You're not. Surround yourself with family members and friends who can and will support you. Get connected with other single moms. Focus on the well-being of your baby which includes having enough self-respect to not take back a man who can't be faithful.
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While it is possible for people to change, grow, and learn from their mistakes, your ex does not have a good track record. He will be in your daughter's life and that will give you a good seat to see if he really has learned his lesson. Actions speak louder than words and, if he is serious, his actions will tell you whether he is trustworthy. Until you are sure, do not let him back into your life as your partner. There is no hurry. You don't have to decide right now. If he will not accept your boundaries or pushes you for an answer, then he is not a good choice as a life partner. I wish you all the best. You seem very grounded and are a good mom looking out for your daughter's interests. Choosing a good partner is part of that, so take your time and make him prove himself. Don't settle for less than you and your daughter deserve.
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