A child has absolutely NO right to deny a love relationship of mother of father with a new partner !
Parents have to accept the choice of partner by their children - children have to accept the choice of their parents as well.
Rami and mum can only have as much love as you give them !!!
Nothing more and nothing less
You have to do much more than to accept the relationship of your mother and her new friend - you have to learn to truly and sincerely love both of them from the bottom of your heart - by hugging them and by asking them for forgiveness for your judging and condemning them.
Each person has a divine right to love and to be loved - hence each person has to be ready to9 accept the one partner willing to return mutual love and to join for life or for as long as God's plan is.
People need a bunch of experiences and many also need lots of "painful" experiences in the dark before being ready to accept God a their savior and beloved one. The absolutely only method for you to help your mother or father is to focus on God and Love and abstain from any even slightest judging them. Let them do whatever they decide and make your own choices if you learn from other people's mistake.
People only can have love if and when they are loved - in this case by you. How else could they have love if no one - even you - loves them?!
God always loves and waits patiently for Billion of years already until more and more of his children find their way back home - with love on a path of love.
Leave your parents in peace for a while and focus on your own inner and outer spiritual development by practicing what I gave you yesterday. That helps your situation far much more than to discuss and elaborate on all the details others might do wrong. Their life is their choice and by the end of their experiences all will be as loving as can be. No one can be force to a certain behavior nor to a certain particular relationship. Freedom of choices is an essential gift of love God gave to all of us.
God bless
hans