I think the best thing to do is take it slow. If you are interested in someone, get to know each other. Don't rush into anything physical. And feel free to talk about the heartbreak you experienced. It will help the guy understand your reluctance to start anything and will show him what things you are sensitive to. In other words, if your ex used to do something and a new guy does the same thing, he will understand if you become suddenly sad or irritated.
But it's also possible that you're just not ready for a new relationship yet. You are still hurt from your heartbreak. While a new man in your life can help you heal and move on from the past, he can also hurt you more. So while I think it's not good to think all men are the same and will only break your heart, I also think it's not good to be too trusting either.
Think about why you want a new relationship. And what you want that relationship to be like. If you need to spend some time focusing on other aspects of your life, that's fine. Hurt people can attract people that want to help but they can also attract people that want to exploit. And I believe that is your fear. Therefore, I would recommend that you seek to help yourself before you look for a romantic relationship. Talk to people you trust and do things you love. Remind yourself all the good things about you.
Don't worry about knocking down your walls. You built them up to protect yourself. Find someone patient and kind who is willing to slowly help you remove them. If they care about you, they will work to earn your trust.
