Boyfriend has child from past relationship he never told me about. I’m so confused and not sure how I feel

Hey everyone, how are you all doing? I’m sorry for a long post, I’m not sure what to do. I was helping my boyfriend set up his phone and needed to pick up a text off there to do that with his permission and just under that there was a text off a woman saying “are you going to avoid knowing your son? This was from a year ago and we have been dating a little over that.

I’m not sure what to think. He never told me there was a chance he had children as he said he never wanted any. If he told me it wouldn’t have been a problem as I have children of my own and also work with children. I tried talking to him about it and he said he never spoke about his past relationships as was too painful. I’m so upset and he tells me he doesn’t want to lose me etc and loves me but this too close to a bone and triggers past feelings from my narc exes.

Am I overreacting and what should I do? I explained to him I understand it might be painful and it hurt me he couldn’t tell me about this and I’ve been left wondering if there’s anything else he’s keeping from me.

I’ve been told by a close friend I need to trust him but I’m struggling at the moment and noticed a little shift in my feelings towards him. Since then he has often been zoning out when I talk to him and appears distant which worries me there are other things he’s keeping from me. I don’t want to overthink and have said I’m here for him but what can I do?

Thanks for reading and any advice is appreciated.