an annulment in the Philippines costs 150,000 the cheapest (£2800) and it depends whether the other party cooperates, if not, it will take forever to settle. and you being unemployed makes it even more difficult to go to that direction. unless she has money to spend for the annulment then its alright. and if you ever do get married, bringing her over here will cost a lot too e.g. processing papers, visa etc..
i hope its not one of the internet romances as mentioned here. and i hope you have met her and got to know her well before you can even decide to marry her.