my gf(19f) and I(18m) have been in an online relationship for 2.5 years. We‘re having a hard time staying together. Any suggestion?

So my gf has been diagnosed with depression, PTSD, and Borderline personality disorder. Her and I have been in a long distance relationship and we’re possibly going to meet next year or the year after. We’ve for exactly 2 and a half years right now and times have been really tough for us. We‘re having constant arguments and I can‘t really keep up with her different personalities and her mood shifts. I really don‘t wanna break up with her as I really love her. I suggested that we do a break where we spend time for a couple of days every months so she and I could focus on ourselves. What kind of break should we have until we possibly meet.