Not sure how to handle this

I had my son in November(2.5 months early). I had a period in February and just found out im pregnant again, while im happy im also having anxiety because me the father have recently split cause he keeps saying im cheating and i haven't. I have been dealing with my mental health since November trying to get my depression and anxiety under control. Im afraid if i tell him hes gonna be mad cause we agreed no more kids (stupid to say when not using prevention) but also because hes gonna deni that its his cause he thinks ive been with someone else. I dont know how to approach this topic with him.