I am being forced to marry my ex-girlfriend

I had a Tausug girlfriend for four years. I am an Ilocano and a Christian then, but I became a Balik Islam a month after we broke up.

We both dreamed and planned to get married when we are ready. The intimacy, trust and love resulted to consented pre-marital sex.

The problem arose when our relationship fell apart and was irreconcilable. My ex-girlfriend forces me to marry her bypassing all pre-requisites of an Islamic marriage to save her spiritually and from the criticism of her family and the community. After supposedly marrying her, she promised to stay away from me and never bother me again. She also promised not to register our marriage to the NSO.

Is this a legitimate thing to do in Islam? I know for a fact that forcing somebody to marry is cultural and not Islamic. But for consideration I will concede to this proposal, what should I demand in our pre-nuptial agreement ensuring that she will not deviate from her promises? What protection should I stipulate in the agreement in case she will find another way to demand something out of our marriage? I can sense that aside from demanding to abide by my responsibility for being a Muslim, she wants to get even with me negatively.

The reason that I am considering to concede is the possible hostility that will be lodged by her family against mine which I don't want to happen. But I also know for a fact, that in all religion, marriage is sacred and that both parties must have that love and trust during the union.

I don't know anything about the Shariah law and if I had already made a mistake, I don't want to make again another one. Please help.

With Islam religion you can have divorce even in the Philippines so even if she register it to NSO when you divorce her it should be recognised, she sounds like she is just trying to protect herself from her families criticism.