Whenever i run into old friends out in public I always get this sense of doom as if this is going to be the last time they see me, I know this sounds weird someone pls help!
It doesn't sound weird to me. It's not nice, but you'd be surprised how many people have catastrophic (expecting the worst thing to happen) thoughts. Many people don't admit to it because of shame, so you're brave to talk about it. I don't know if you've ever spoken to a counsellor but a useful thing to remember is that thoughts are just thoughts. Just because you think something that doesn't mean it's going to happen.
Try some reverse psychology on yourself. Think of something really happy but unlikely, do you believe it will happen just because the idea popped in to your head? Another thing to remember is that thoughts do have a powerful physical effect on you, unhappy thoughts are exhausting. So next time you have one of these scary thoughts or feelings, counter it with a happy thought, or even a silly one, make yourself giggle to break the tension.
Best of luck!