Will I always be the one who does the work while he continues to behave in an unhealthy way?
Going on 21 years here, so I can answer Yes and No. Yes, you will always be the more emotionally capable one in the pair. That's not to say you will always be able to be a perfectly reacting robot, nor should you be, but you are by nature already the more self-aware person, and the more emotionally stable one. And with that said, you will always be doing a lot more of the work.
I liken BPD to emotional diabetes, simply because both are conditions that do not go away, they are with that person forever, and both require maintenance and can benefit from assistance from a spouse.
My H is emotionally disabled. He cannot shrug things off, self-soothe, easily. Small things for me can feel like huge issues to him, and he lacks something that I have that enables me to put things in perspective, and for H, all feelings are truth especially at the moment they occur - there is no past, no future. Lessons and skills many other non-BPD people learn as toddlers and teens are not there. H has almost a form of limited object permanence. H has limited concepts of how to let things go, how to have both good and bad impressions of people simultaneously.
Knowing this, I tell people on here I would not get mad at him is he had no legs for not being able to change the porch light on a ladder, so I try really hard to not allow myself to be hurt when he can't/won't keep his emotions in check, manage them reasonably, and express them in a non-abusive way.
Since I've been coming to this site, and working on being less codependent, and letting H be responsible for his own feelings and stopped as best as I can from trying to manage his feelings for him, he HAS improved. He went from being a guy who quit his job without a second thought because someone sassed him, to being a guy who was willing to work long hours to make up time he took off so he could finish school. He went from staying home all day in a depressed state to a guy who still struggles with depression but makes himself go to work to help fight it.
So as you improve, your H can't help but come along for the ride at some point. There will be a delay, like you're tethered on a rubber band or bungee and as you stretch away, he will snap to you eventually. Then you move to the next step, pick another boundary, and work on that one.
Sometimes I don't want to be strong. I want to be vulnerable and taken care of and just loved for being me.
This can come. You will most likely still be the stronger overall. But as you get healthier, your H will have to learn new skills to deal with your new normal, and he WILL be able to give you more than he is able to now. Sadly, it's a bit like a toddler needing to learn to walk, and can only do it when Mom walks away to give him a goal to reach.