Kabit or kabet means the other woman or man, mistress, or the side chick... or a lover, especially the illicit partner of a married person. The oi is a particle or an exclamation that roughly translates to "for your information;" it's usually spelled uy.

Here's a breakdown:

sa ako  |  na   |  kabit/kabet            |   oi

to my   |  that |  other woman/man  |  for your information

"For your information, that belongs to my lover/paramour."

Hope this helps, Melmon. 

Ug as aku.ang mga higala nga aduna pa'y ikadungag o gusto bang itúkmà aku.ang pagpatin.aw, palihog na lang ug tubag pod.