The important thing is that you recognize your BPD. It's never going to go away, but you can do so much to manage it when you know how it operates.
It's going to be natural to feel these feelings because that's just how the nature of your illness is. It's not your fault, but it is an added responsibility you have to handle.
This jealousy is going to pop up from time to time, because that's how your brain is wired. But you're doing pretty well for yourself to own it like this. Your brain is hardwired to want to put the blame on someone else for emotional state, so the fact that you can so readily identify this mechanism isn't toxic at all. It's a sign that you've made a good deal of progress on your health.
That doesn't mean you're going to feel any less shitty for a while. I think these feelings are an opportunity for you to realize that the only person responsible for your happiness is you. If you want to spend time with your best friend, suggest a time to hang out or schedule something you're both interested in.
Sometimes being a friend means letting our friends make their own choices and find their own happiness in life. It's not always going to be the way we want, but our job is to love and support them for as long as we have them. What else are friends for?
