Convincing my parents for love marriage- 4 years of love

Hello.. I am in a very bog prblm since an year or so. Im in love wid a guy frm d past 4yrs n he too loves me a lot. We understand each othr very well that he feels fr me as his dghtr n I feel fr him as my son. We nvr had any fights he cares a lot fr me..
I had to tell abt my love at home because they were in srch of an alliance for me. My parents got shocked on hearing abt my love n straight away denied for it. Lot of misunderstandings n fights happnd. I got into depression & got treated for it wid d psychiatrist. Dey want me to marry a guy of our caste. The guy is frm othr caste. Im nt able live widout him. My parents made me to leave my job as we both wrkd at same ofc..
N d othr prblm is one of my relative got eloped during her teenage sme 15yrs back. All d family had to see a very bad tym because of dat. Dats also one of d reason my parents are nt supporting my love.
The guy's parents have accepted me n dey will b marrying their son wid me only on my parents approval.

Pls pls help me in this situation.. im depressed badly. N I gonna leave everything n stay alone fr sme yrs. I cant ever marry any othr guy xcpt my love