Secrets and betrayal

I have been with my fiancé for about a year and a half. We got engaged pretty early in the relationship and on our one year anniversary we moved in together. It’s the kind of love out of a fairy tail, after the hell I went through in my previous marriage. Well we did have our ups and downs but mostly it’s been great. So at the beginning he did tell me he has 2 kids, which I met them and love them like my own. It’s been bliss, they are wonderful. We do everything with them. He loves the fact how much I care for them and them for me. It’s a strong bond we share. So we decided to start trying for a little one of our own, but still that hasn’t happened for us. Which is understandable since I was on the pill for so long. The shocker came today when we sat down for dinner and he told me he had something he needed to tell me. I didn’t know what to expect. So after and year and a half he now decided to tell me that he in fact has 3 kids not 2. He said he didn’t tell me about his oldest kid because he is not in that child life. I understand the fact that he is not in the child’s life, but at the end of the day I feel so betrayed by him not telling me this earlier. The fact that he has another child doesn’t bother me one bit, what bothers me is the fact he lied to me and hid the 3rd child from me. I asked him at the beginning of our relationship how many kids he had and he said only 2. Now come to find out it’s 3. Why did he feel the need to lie? He broke my trust. We been trying for a child and I didn’t even know that he has more then he told me. I honestly don’t know if he is hiding anything from me. But at the end of the day, I called him out on his lying and told him it was wrong he lied to me about it for so long and told him that his secret hurt me. Again I don’t mind he has a 3rd child, it’s the fact he kept him a secret and lied about it. Now he broke up with me because he said I’m acting unreasonable and he doesn’t understand why I’m angry with him. And instead of him to man up and take responsibility for his betrayal, he broke up with me and said I done much worse. He throws my 1 time mental breakdown in my face every time we argue. I been getting help with that since it happened and it never happened again. I just feel lost at this point and don’t know what to think or do. Help please