Ladies what should I do in this situation?

I no longer trust my boyfriend and yesterday I told him I want to end things because he’s a big ass liar. He was texting his baby mother on and off last month but she had him blocked. He kept texting her periods and saying hello to see if he was block still. I said why was you texting her and the reason why I asked because before I seen messages of him flirting with her. So he said remember they was in a fire and lost everything and I was just texting to see how my son was doing. I looked back at our old messages to see the exact date because he told me the situation and I said let me know what I can do to help. He told me his son sizes that day he texted me about it. And how he knew about the fire is because his siblings keep her in contact and she basically don’t even want to talk to him because he’s careless and a liar as she say. So yesterday he tells me the reason why he texted her is because to check on his son and I seen the conversation he had with her and he not once mentioned his son. She was on his back about child support and how he’s barely making payments and I been telling him he needs to put his kids first. So she has a warrant out for him. I said if you was so called texting her to check on your son why you didn’t even mention him in the conversation he said I wasn’t trying to deal with her negativity I said you should have told her if you was making payments that the money is on it’s way and ask about your son everything else is irrelevant. It’s about your kid and plus he said he didn’t ask about him because he got all the information from his siblings I said exactly! You still texted her after the fact you got his sizes and all! That’s why I don’t trust him because he will lie about the littlest thing. This is suppose to be about his son and he will try to be sneaky with the text between him and her he’s protective over his phone anyway. And I know I shouldn’t be in his business but he’s being sneaky about stuff at times and I refuse to be with someone that wants to be sneaky