FP, I'm with Caps in that while I don't come close to your game, I've been where you are, including the -35BI swing. I know mine has far more to do with leaks than yours, but there was enough cold deck, run bad variance in there too.
I feel like I'm a "student of the game" in that I have a large and constantly growing collection of books, a hard drive full of ebooks and videos, and I try and soak up bits of knowledge from the experts like you and Belgo and WVH all the time. At times I'll run good and think it must be because I'm learning and getting better, only to be slapped in the face again. The result is that I'm pretty sure I doomswitch myself from that point on. Instead of continuing to play through it, I very subtly tilt and convince myself that I must be doing something wrong, therefore I should CHANGE AND CHANGE NOW! I start tweaking parts of my game that I shouldn't touch, which makes things worse. Rinse, repeat, and it snowballs from there.
I've been on the -30+BI swing maybe 3 times in my
online poker playing career. After the first time, I ditched cash and played tourneys, where I actually did very well -- made several times over my cash downswing, withdrawing most but leaving a nice online BR to take a shot at cash again. I did well for a month or two, only to experience another dark slide. This time I dug in and tried to fight it. I got WVH to sweat me and took his advice to heart, and my graph took off northward again. I thought I'd figured this thing out finally, and for weeks my graph barely dipped. I was putting in huge volume (for me, with a full-time job and family) 9-12 tabling 50NL, made Iron level once and Silver & Bronze several times. Then I started bragging in the monthly cash threads and posting graphs -- which was the kiss of death apparently, LOL. April and May were major losers again, and after draining all the profits I had earned back over the previous couple months, I just melted down.
So I took a break. Forgot about Ironman and trying to top last week's RB payout. Just play when I feel like it. I joined the CC Spring League on a whim and have had a blast with it, it made me want to play tourneys again. So that's what I'm doing now, and while I've yet to be hugely profitable at it like last year, I'm doing okay and it's a helluva lot more fun for me now. I'm sure I'll take a stab at cash again -- maybe on Stars as a change of scenery -- but for now I'm just relaxing at it. Mid-year Ironman bonus at FT is starting in a couple days, and even though it's free money, I'm not even sure I'll chase it -- I've lost far more than that bonus amount over the last couple months, so the bonus wouldn't come close to replenishing it and I'm likely to just tilt off even more.
Nothing there in the way of advice I could offer you, just some commiseration from someone else who knows what a -35BI swing feels like. Although your BI's are quite a bit larger than mine.