My mom doesn’t like my boyfriend

So my boyfriend and I have been dating for almost 5 months and my mom has wanted to meet him since the first week we started dating. We started dating towards the end of the school year, but we’ve known each other months before. I’m a busy nursing student and this is the first real relationship we’ve both been in, so we decided to not rush anything. We live 3 hours apart and we both have full time jobs, so it’s hard figuring a day out to see each other. My mom said that if she didn’t meet him by the end of the summer then she’d like us to break up. Neither of us really wanted to meet the parents that early on, but my mom kept hounding me and he was very sweet and drove up on his only off day that whole month to see me. That didn’t impress her though. She thought it was odd that I didn’t meet his mom yet and we decided to wait until we go back to school to see each other again (because we work pretty much everyday and school is expensive haha). She thinks I should start seeing other people, but I’m 20 years old and I think I should make my own decisions about this situation. She keeps nagging me on this and says she doesn’t feel right about this at all. She keeps showing me her friends’ sons on Facebook and asking if I could date them instead. She doesn’t even respect that I’m in a relationship. She says it’s not even a relationship because it’s long distance and she keeps implying that I should cheat on him. She’s so unbearable with this. I want to talk to her about this, but I don’t know how to! She’s like a child! What should I do? I mean I only have 24 days left until I move back into school, but I don’t know how much longer I can take!