Sex after becoming a mom

So I haven’t had sex in, well a very very long time, probably not since the night my son was conceived (to be honest 🤣) me and my sons dad aren’t together and I’m finally wanting to get back out there, not looking for anything serious just some flings but I am BEYOND terrified to have sex! This guy I’ve been talking to has a huge dick, let’s just say the idea terrifies me but I want to do it. How do I become not so nervous?? I have never really had a lot of sex, and have only had like 3 sexual partners and I feel so embarrassed! I also have had some pain before while having sex, like in my stomach area and am nervous with someone who has a bigger dick that the pain will be worse, idk why I get pain, but sometimes it’s unbearable hence why I never really have sex