Infidelity - common law wife

Hi Atty. I am in a relationship for almost 12 years now, and have 2 kids with the same guy. I am 38 now and he is a couple of years younger than I am. The man who I met and worked with before is in overseas for 4 years now. There are plans to marry but still in wait for a petition from family living abroad. Our 12 years of relationship is one similar with real married couple, however when my youngest who is now 3yo was born, I went thru depression which I thought was just normal for mothers like me - all the while I have been updating him of the feel I have but he always just remind me that he and the kids are who I need to focus on and everthing will be okay. Never have I thought that during the past 3 years, he's been in constant chat with another girl from the same company we were before. Early last year, he made a loan which part was spent to process visa for the other girl, who by the way has one kid and is separated from the kid's father. The girl is now with him although they cannot live together because I have relatives who are living together with him. Even during those times he started relationship with the other girl, ours has almost been the same. I only found out about the girl about a couple of months ago. I started having a different feeling logging in to his messenger finding all his sweet messages to me deleted from his user leaving only those for kids. And so when he flew back home 2 months ago, I intentionally took his phone while he's sleeping and made search of what was going on. I have quite a bit of a talent for apps and restoring anything deleted so I did, and was able to export all messages and pictures they have for the last 2 years. Needless to say, the hurt is something I never thought existing- I asked him about the girl with all my might and faith with the Lord calming my self down so I can get the answer clearly from him. He admitted to have learned to love the girl but not enough to leave me and the kids as we will always be his priority. He promised to make sure to end what he has with the girl the soonest, saying the plan of a garden wedding next year still remains. I asked him about his promises of not leaving the girl whatever happens, and he said they were all "bola" - not true.
Got about 300plus pics of them - hugging, kissing and posing like true couples. Some are pics of the girls kid I guess bec the kid is here with her parents.
The chat I got contains everything, from sweet messages to something I never thought he would do with another girl other than me.
He is back overseas now for a week, and I feel he still has not made any effort to end everything about the girl. I read how the girl make an effort to make him feel bad about leaving her for me whenever I try to call him. Their quarrels about prioritizing our needs over finding time for her whenever she asks him to stay longer on her pad. Also read about the girls often bad mouthing me with how bad I look compared to how sexy she is and how good is she in bed. The girl by the way is 5years younger than him - 8years younger than I am, she's about 30yo.
I want to keep the family for the kids - of course because I still love the man I have always imagined to be my legal husband.
Atty., what should I do po to make the girl realize she has to stop this? Is there anything I can let her know I will file against her if she does not stop from staying away from my man?
Thank you in advance po. Ash

I don't recommend you contact the other woman. This usually leads you to do something rash and suddenly the tables are turned on you for something like cyberlibel or threats. In my experience, doing something through legal processes will result in break up of the marriage.

However, if you do wish to proceed. I recommend you hire a lawyer who will write to her on your behalf, informing her that you are aware of their relationship and threaten her with litigation.