To null and void my marriage

Hello...
i am 28 years olds..im currently working..
i just want to share my story and hope you can give me and idea or what should i do in my situation..

i got married last december 15,2007..
i have two kids,, 5 and 4 years old...their carrying the lastname of my husband, but for myself i do not... i still use lastname when i am single..
this is what happen, and i decide that i have to use my last name not the last name of my husband..

since we got married... he is so irresponsible..
he has also engage in some affairs not once but twice...
he also stab me infront of my kids,,due to that i found out that he is involve in an affair..on that date,months and year i left him and go back to my house, my parents house... i remember the year it was 2012 march that i left him... now its been 2years...
he doesn't support me financial,,but its ok because i myself can support my kids and give them there needs and there wants...
Now, i found out that he has a live in partner and they also have one kid..Now i just wanted to make a clarification with him,,,
i just wanted him to sign a papers,, stating in their that we are not husband and wife anymore...so that he will not be included in my benefits....or what..

do i have the grounds to do this...

thank you...

any document which you will execute stating that you are terminating your marriage is void and will have no legal effect. kahit pirmahan pa nya yan or kahit ipanotaryo mo pa yan, walang bisa yan dahil labag yan sa batas. tanging ang korte lang ang makakapagterminate ng marriage nyo.