Finding out I have a brother

Hi, I’m fairly new here and really struggling with finding out I have an adopted brother. So for background, I’m a 31 year old female living in the uk. I was been bought up by my mum with my sister who is 34, neither mine nor my sisters dads have never been around (hers died and mine is absent for whatever reason he fancies at the time) and my mum has (understandably when you know what she’s been through) issues with men and relationships. A couple of years ago my biological cousin on my mums side signed up to ancestry, her mum (my mums sister, my auntie) knew but apparently didn’t think anything would come of it with regards to my mums other son (who I knew nothing about at the time and neither did my cousin) Ancestry matched my cousin with a first cousin who’s name she didn’t recognise. She apparently thought someone had had an affair on her dads side (lol!!) but messaged him anyway and heard nothing back, she told my auntie who told her it must’ve been a it must be a mistake. Anyways a year later she had a response and my auntie rang my mum to say she had had to tell her daughter (my cousin the truth) So... sorry for how long winded this is btw my mum obviously had no choice but to tell me and my sister that we have a half brother whom she had been forced to give up for adoption when she was 16. My mums parents were extremely religious, her dad was a vicar and had not given my mum any other choice. I am so torn between feeling absolutely devasted for my poor mum who has never recovered from this and has carried such a heavy loss through her entire life and feeling selfishly hurt and betrayed that I was never told and am now in my 30s trying to figure out my life which feels like a big lie. My whole family knew and they kept it from me and my sister for all this time which I know was my mums choice but I still feel hurt by them all, why?. We got in touch with X just before Xmas and I’ve had some contact from my brother via email, text and 1 phone call, I go over the phone call in my head all the time questioning things I’ve said, ‘should I have said this or that, did I say to much, did I listen to him attentively and ask the right questions.’ I feel like I’ve driven myself mad with it all. My mum and sister have also had contact via the same methods. He seems lovely, said he holds no resentment at all and would like to stay in touch however he’s no longer answering or even opening my messages although I can see he’s been online (I’ve only sent two in the last month but he has been pretty quick at replying previously and also has messaged first a few times) so I’ve left it for now. I’m not sure how I should be behaving in regards to maintaining contact, should it be down to us - the family that haven’t been there, to encourage a relationship of sorts or should we let him completely set the pace. Either way is of course fine I just worry that I’m not doing enough. Im trying to be neutral with my mum too and I’m trying to be there for her, letting her offload how she feels and encouraging her to get some outside support via councilling that she so clearly needs, she is struggling but I can’t help but sometimes feel angry - not directed at her and more with her, I think?. I feel that how I see my family as a whole has now completely changed. My partner is stupidly optimistic about it all and says it can only be a good thing that we all know now, which is true I suppose? So why do I feel so challenged, changed, confused and hurt by it all? Many thanks for reading this far even if no one sees this it feels good to write it down and get it off my chest xx