I think Ookami is right, it's a lesson I wish I learned at a much younger age, but for me it's not healthy having people who invalidate me like that in my life. I'm really sorry that they have treated you this way. In my experience with these kinds of things it isn't your fault, I find most people just aren't capable of being there for us like that. I think venting is very important though. I've had a lot of similar issues with friends and family not being there for me, it can be really hard and isolating. In the past I've sought out therapists for just this reason. Idk if that's something that's available to you or not but it might be worth considering if you really need someone to talk to.
I see you are new so I'd like to welcome you friend, we are happy to have you here. This is also a good place to open up if you need it, most people here are very understanding and accepting. I truly wish you the best.