Suicidal thoughts & emotional restrictions from girlfriend what to do

- Am a career oriented guy, just graduated, been in relationship almost 4 years, both majors - initially discussed marriage, though intention was there then, never committed - consensual physical involvement - had differences, most times I gave in to her wishes, secluded myself from socialising too - she had an affair in 3rd year & so I told it wont work for us - she spoke about suicide & wanted a chance, we continued but with more differences - now, she wants my career choices to be according to her wishes, else she again talks of suicide coz it might affect marriage - after those incidents, I am clear this relation wont work for me now but she says more about her suicide, emotionally & mentally disturbing me - I want her to move on peacefully but she intimidates me (she once said she attempted suicide in her relationship in college 5yrs ago) What should I do & how exactly (procedure)? I dont want trouble nor I want to inform my parents. Please advice in detail. Help Thanks