Partner & mental health.

I feel so so bad. My fiancé deserves an amazing life, someone that is joyous and happy that will make him happy. Im in a rut i cant seem to get out of. My dad is a drugged up pedophile and rapist, my mum and her partner are extremely toxic/emotionally abusive and he is a narcissist (they are now estranged) and using my sisters as a weapon and we lost our first child in November after ttc for so long with infertility. Im a mess and the guilt is eating me alive. He had a normal upbringing, a relaxed normal life, then i came along and all this shit and drama was part of his life too. He has actually got grey hair since we met. I dont know what i would do with another loss but i feel its a selfless thought, to break him free of my negativism, even though he is obsessed with me, would do anything for me and were madly in love. I just want whats best for him and for him to have true happiness and a life he deserves with a woman that can provide him with a family😞. What would you do?