Be Selfish or Be a Good Friend?

So if you’re pregnant like me, and you probably are if you’re reading this, you may have found that your focus has been shifting more inward and are perhaps finding it difficult to stretch your empathy as far as you used to. I’m an incredibly empathetic person so I FEEL uncomfortable when my friends do, and I always have been a very supportive person for my friends to vent to, etc. However, I am finding it hard to find the right words to tell my best friend, who has been having a lot of tough problems and feelings, that I just cannot help her at this time. I am due in less than two weeks, and I find the constant trickle of negativity really hard to navigate. Like, I just want to ignore her texts honestly, but how can I? Also, I don’t want to just brush her off. BUT, I am feeling really sensitive to any bad news, emotions, and negativity that can trigger my anxiety (generalized anxiety disorder). How can I be a good friend but also tell her that I just can not process any more bad vibes at this time?