I don't understand why someone would go and have sex with other men when they have just had a baby with their husband. Being unsatisfied with your sex life at home is one thing, but looking for satisfaction elsewhere and getting it is another.
Why not talk to him and try to discover new ways to bring the spice back into your sex life, together. Having a baby can take away the interest for a while but it wont be gone forever. You chose to have a baby with this man and to marry him - he must mean something to you. Why is your new family not more important to you than sexual satisfaction at the moment? Try and be faithful to him if you want your marriage and family to stay together.
Having a kid can really change things, and put a huge strain on a relationship. The first few months are particularly hard. First of all there's the sleep deprivation, which can bring out the worst in anyone. Then there's the change of roles, particularly when the mother has stopped working to care for the baby full-time. This can lead to resentment on both sides about how much the other person is contributing. The husband can be jealous because all the attention that used to be given to him is now given to the baby, and he feels like he's missing out. Women often lose their sex drives completely for a month, or several, after the birth; by the time it returns their husband may have lost his, or given up hope of having sex with his wife; then the wife can feel hurt and upset that her husband doesn't fancy her any more and blame it on the change in their body caused by pregnancy and childbirth. And that's just for starters. You may have experienced one, or more, or all, or none of the issues I've bought up - they are just ideas, I don't know enough about you to know which ones may apply.
So, what you are going through is far from unusual (although it's not that normal for the wife to have sex with other men as a solution - or was that just before the baby? Or both before and after?). You need to talk together. You need to make an effort to spend time together that does not include your baby, so you can be a couple again. This isn't easy, particularly if you are tired all the time, but if you can make the effort it will be worth it. You need to make a commitment to ride out this difficult period in your relationship - if you can ride it out, it will get better in time.
It's easy to fall into a routine at home or get so used to each other you start getting upset over silly things. Marriage can easily be ruined if trust is broken and you're unfaithful. Perhaps you should come clean with your husband and if you still want to be with him, explain that to him. Tell him you're sorry and that you'll work hard at your marriage. Try getting someone to babysit your beautiful baby girl and go out at least once a month for a nice date so you can have time to yourselves and not worry about anything other than being with each other. It might take your husband some time to forgive and trust again, but it will be worth it if you two love each other. Honesty is always best so be honest with him about what happened and be honest with yourself about what you want out of your marriage. If you want to save it, try your hardes to. It's always worth it, whether it works out in the end or not. Good luck :)
Instead of turning to someone else,put the energy in your relationship. communicate with each other. is he feeling the same way? do you know? relationships are ever changing and you have to work at them. they do not just happen. It is very easy for them to lose flavor and become mundane. how much does the commitment part of marriage mean to you? how important is it to keep your family together how much effort do you wanrt to put out to save it.? answer these questions as well as why did you marry him in the first place?