please advice me on what to do

Hi.
Please help me in this situation.
My husband has another woman. And he got her pregnant while we are still so much together. We are legally married and have a daughter. Last year, I found out that the girl who he keeps on texting was pregnant and she gave birth August of last year. It was so hard for me to accept that, but I gave him another chance. And we are still living together for the sake of our daughter. I know they are still seeing each other from time to time but I just let it because of their baby as well.
Now the girl is acting wildly sending me messages and threatening us. Saying that she will bring their baby to our house (we are living with my parents) and make some scenes. I still have her messages in my phone. I changed my phone number twice but she was still able to know about it.
My husband doesn't seem like to fix their differences so I am really afraid about the scandal the girl might create on our family.
Please help me. Sa tingin ko po ako na ang naagrabyado ngaun ako pa ang nadadamay sa ginagawa nila. Ang gusto ko lang pong mangyari ay wag nya kami guluhin ng anak ko. Nakakaawa po ang anak ko kung makikita nya tong pangyayaring to. Anu po bang legal way para tumigil siya? Noong una wala po akong balak na idemanda sila pero sa nangyayari parang ko pa ang may kasalanan. Anu po bang pwedeng i-file na charge against sa kanila?
Please help me. This situation has really cause a lot of stress to me.

is your husband carrying on with their relationship? is he providing support for the child? why is the mistress acting that way? what does she want to happen?

what i've done for my clients is to try to propose some kind of resolution which is acceptable to all, as much as possible, then send a demand letter to the the mistress to cut it out or else face some form of legal action.

arguably, you can charge her with threats, unjust vexation and for monetary damages for interference in your family affairs.