Relationship counseling required. I do?

I have been in a relationship from last 6 years but my partner started hating me few months back and started affair somewhere now she is indulge there and I feel so painful she think I am strong enough to face this and says to me everytime to lets be friend otherwise I will die. I can't live without you . Now she tells me I am going to help that guy or meet him for some work then I feel so painful they went to hotels as well. She told that I see u as a friend so let's be friend when I try to breakup and separate then she starts behaving stressful , crying so what should i do ? She says ur value will be always on top for me and you also do the same wherever you marry don't degrade my value in your life so what should i do.that guy is soo innocent as per her she keeps on asking me to help and i do him help also as he is poor also but it gives me immense pain when I think about them and their activities which they do secretly from me