Why does my dad get in my face or get upset whenever I talk about my mom?

Whenever I speak about my late mom that abandoned us, I either get cut off or people ignore me and walk away. My dad has scold me off for bringing up the past. He is tough as nails and he refuses to let me sulk in pity or depression. He would me like, “Stop dwelling on the past and I’m not going to let you. Not on my watch. If you keep bringing it up, I’m going to be hard on you. Your mom doesn’t want you. Let her go already!!! You don’t need her.”
I feel like he’s too mean or too tough. I talk to someone else for sympathy because it’s hard to talk to my dad about my absent mom. My older half siblings flat out told me I need to stop bringing it up and they’re tired of it and Dad HASto be tough on me because I have been upset enough and sometimes it’s the only way to get me to listen and snap into reality.