well, that was just a very childish thought he had, he felt incredibly scared and alone and he just wanted his mom. also, i think before she raped him, she was actually very sweet to him and sort of a good mother, so he probably used to feel genuinely safe with her, that's why he misses her. oh and there is so much lore i didn't get to explore in the fic thats just sitting uselessly in my head lmao but she was not mentally stable at all. she was probably also abused by her husband and brother in law (i dont exclude she might have even been a close relative like a sister or a first cousin) so she had her own issues too.