He said she is his girlfriend while I am his wife-to-be.

Good morning aunty amara, good morning to all. 
please i have a question and i need matured
minds to answer me 
I went to visit my date
in his house i met a girl whom he told me was
his sister from the same tribe i didn't say a
word but he asked me to kiss him so that the girl
would get upset & leave i refused because with his
statement i sensed something was wrong somewhere after some
weeks i saw the same girl's half naked pictures in his phone. 
I didn't say a word but he noticed that i was angry
so he opened up and told me that she was his
girlfriend and am his wife to be.  
Can you imagine that,  i got upset and told him is over he called me on phone and i sent him a text to stop disturbing me but just can't cope without him, i think abut him every where i go. 
My friends said i over reacted is that true, please 
advice. 

Dear sender, 
Will your friends be there when you and his girlfriend would be carrying his children? 
Will your friends be there if you contract Sexually Transmitted Diseases? 
Will your friends be there if he ends up with his girlfriend while you the wife to be becomes wife not to be? 
But on a funny note, your boyfriend must have mastered the art of division of status to smartly give you the bigger title and his latest his girlfriend. 
Anyway, a cheater is not and never worth your seconds cos there may be another story in the next second. 
Please do no permit your friends to ruin your happiness with their opinions. 
Be wise and be focused. 
You should know better what you need than your friends do, please go for a partner who would make you happy.