I wouldn't force yourself to do acid if it's already gone badly. It may go better the second time around, but if you've already got it in your head that it'll go poorly, then it will. Mushrooms are way milder, though, and I don't think I've ever had a properly bad trip on them. I've had difficult ones, but that's because they crank the introspection up to a billion percent of your baseline and sometimes that leads to you realizing things you don't want to realize.

There's a scene in Venture Brothers that actually describes it well. Rusty's working with Henry Killinger, who tells him to step into his Magic Murder Bag. Rusty asks what's in the bag, and Killinger responds "only what you take with you." Psychedelics are kinda like that. If you have your baggage at the front of your mind going in, then your baggage will be the focus of the trip. If you go in with your hopes and dreams front and center, then that's what you'll see.

YMMV, of course, but having talked to others about it, that seems to be a fairly common theme.