Unregistred marriage

already you have completed 8 months of marriage for applying for divorce you must complete one year 

contested divorce may take more than one year and for mutual divorce withing 8 months the process will complete and for mutual both should attend for divorce personally in court two times 

you take it advice or think as legal option first already you completed 8 months then for this four months try to take separate residence and try for some time and then decide ( i know at this time you should be with your parents but to settle some issues you have to take this step) and even your parents will be happy that you are happy in your married life

about the marriage you do not require any certificate to apply for divorce 

I agree with Mahesh... Give it a try leaving separately. See what happens. If things do not work out, then and only then, go for legal proceedings.

In the meantime, be careful. If possible, start accumulating evidence of her cruelty to you but you must balance it properly with your desire to make your marriage work.  If after you stay separately, things still do not work, well... you have the evidence, you know what to do.

wait wait

you said "hindu and catholic customs"

what do you mean?

who is hindu who is catholioc?

who converted to other religion?

whether conversion was before or after marriage?

whether hindu went to church to marry catholic?

whether pandit performed fera of catholic?

all these facts are vital to see if at all any marriage has taken place.