Hi, there.
I agree that you shouldn't be so hard on yourself.
That said:
I know what you're thinking, just don't lie. It seems very easy, but I have learned that reading about BPD and learning about it is completely different than living with it. I never know if what I'm doing is right. It doesn't matter what happens or what is said, in her eyes, if my love is real, it should never ever waiver despite how I feel in that moment. My love should outweigh everything, and my behavior should never change. She says I don't validate her enough, but part of me, deep down, knows that a good portion of it is due to how she see's herself.
This portion of your message really stood out to me.
There appears to be much to unpack here.
First you say you know you shouldn't lie.
That is definitely a fact when you are trying to maintain any type of relationship with a BPD because it is already extremely difficult for them to build trust. But then the rest of that passage kind of glosses over the main issue in the eyes of anyone with BPD - the lie.
You go on to say that in your partner's eyes, your behavior should never change. Then you mention her need for validation. As significant as validation is for a BPD, this seems to be a separate issue altogether from trying to rebuild trust.
Has the main issue happened before?
By that I mean has your partner caught you lying before?
You mention that you grew up lying to avoid arguments but I don't want to make assumptions.
I myself had a rocky childhood so I wasn't exactly a clean slate when I began dating.
In my experience, we non BPD get so caught up with our partner's illness that we end up blind to our own unhelpful and unhealthy habits that would be harmful in even the healthiest of relationships with the healthiest couple.
It took me a lot of work of my own with a counselor to realize that I was regularly triggering my partner without knowing, stemming from learned behaviors from previous toxic relationships.
Reading your post tells me you could really benefit from working on yourself too. You wrote many absolute statements and listed her flaws which are common for a BPD, then you asked for guidance. You didn't explain why you said you know you're not completely innocent. It sounds like there is more here than the lie you mention upfront.
I'm not saying you need to tell us all that you have done. I just say that because I used to sound like that before I finally gave in and sought help for myself independent from the relationship. Actually, it was supposed to be for the relationship first but therapists have a way of making everything about you.
My partner would repeatedly tell me what I was doing wrong and why it was so damaging to them and their attempts to get better.
But I really didn't see it. I just saw their rage and unhappiness as irrational.
That was all I would focus on.
As embarrassing as it is to admit-there were moments of gaslighting on my part that I would never have realized if I hadn't kept a journal at my counselor's suggestion and then gone over my entries with him.
I also didn't see that I was doing what some BPD partners do myself!
I wasn't taking into account all the times I would do unhealthy things any partner would be bothered by that didn't end up turning into huge fights. My partner would be suddenly quiet, but not angry. And then I would get in a bad mood. Meanwhile it wouldn't even occur to me that those moments meant my partner was actively fighting through their initial reaction instead of starting the usual pattern of blowing up and getting explosively angry then shutting down for the next two days.
From the small amount of information you've shared, especially the very beginning, I would recommend that you seek help for yourself and your own traumatic childhood first. You need to be healthy yourself before you can help her or even try to understand her illness.
this is because while it is easy to read things and try to look for symptoms so you can figure out how to fix them or how to get her to believe you and feel valid in your eyes, when your own reality\perception is already clouded by childhood trauma, it is impossible to see anything clearly.
Especially anything as emotionally intense as a relationship with a BPD.
Hope this helps.
Sorry for typos.