Need advice on Pregnant and Single

Good day moms,

I urgently need some advice and not sure who to ask. I am already a single mom of 2, and I was dating this guy for 2 months and found out recently that I am in fact 6 weeks pregnant. When I told him, he happened to come clean that he has another girlfriend that lives with him. I am keeping the baby and going ahead with this even tho he wants nothing to do with me or the baby, do I tell his girlfriend whom is living with him whats going on, or do I walk away. Please help. I am going crazy and not sure what to do