I've struggled with this before my self, where I would run a disastrous session and feel like shit about it for a while after. It happens to all of us, it's not a personal shortcoming- We all make mistakes, and your friends aren't mad at you, and they understand you. 
Quick 2 bonus tips:
If you're the GM, try to get the players in your games to be GMs as well. Either invite people to your game who have experience GMing, or encourage your players to try running a oneshot. They'll become better players for it, and understand better what it's like to be behind the GM's screen.
Shortly after every session, write down what went well and what went poorly. Put it away for 1-5 days (before your next session) and then reflect on it.My worst sessions ever are seared into my brain.
But hey, I'm still here, running the best games of my life lately, especially now that I'm trying rules-light games instead of DnD
Always have an exit strategy. I've practiced donning my gas mask and packing up all my books and materials in the time it takes for a standard SOLAS smoke signaling device to burn out.
Not a ttrpg guy here, sorry for barging in but what makes a DnD game so bad? Like people keep rolling 1s and everybody dies or the story is boring or what?
Having run a bad D&D campaign before, you can bog the plot down in dumb ways, make poorly calibrated and repetitive fights (it is fucking hard to make good fights in D&D because the system is extremely obtuse and has no clear rules about target numbers and player stats to let you make appropriately scaled generic enemies flavored however is narratively appropriate, so you're left trying to mix and match a handful of narratively appropriate monsters from the big list of pregenerated monsters based on horribly inaccurate rules of thumb by party level), or get lost in fiddly little details nobody notices or pays attention to because there's a world of difference between setting the scene of a ttrpg and setting a scene in fiction writing.
There's also the option of running a pregen adventure, which will be even worse because those are awful and even harder to run than just winging it is.
Really D&D is just not a good system in general, being overcomplicated for how barebones it is and overdetailed for how generic it is. Does anyone need hundreds of pages of spell entries that are just different flavors of direct damage combat spell, tiers of the same utility spell, and a ton of super niche effects that no one will ever think about taking because they only get to know a handful of spells and have to prioritize taking damage spells to remain viable? No, it's fucking awful and even Pathfinder - which does it a bit better - still runs into that same core problem of "99% of this stuff is super niche, so I guess I'm just sticking with the straightforward damage and CC spells that'll actually get used." Does anyone need a thousand pages of shitty monsters that are fully statted out in ways that are 99% redundant, from which DMs are expected to build encounters where literally the only numbers that matter are health, its attacks, and its AC? Nope, not even a little.
I've also run the odd bad Shadowrun game, but that's a bit harder to mess up because of how much easier it is to stat out generic enemies with a basic understanding of dice pools (they just get 6-12 dice for a check as narratively appropriate and that can just be decided on the fly instead of written up, anything higher and they're probably something that needs an actual stat block). That I've messed up by fiddling with plot ideas too much and making a run end up nonsensical, or by letting combat bog down into a multi-week ordeal by tracking movement and exact positions - never ever do that in Shadowrun, make it fast and dirty so the combat's done in half an hour instead, and anything more involved should be handled narratively with generic skill checks not fiddly "ok you can move up to 100 feet this turn" shit.
I use DnD as a catch all term for rpgs, but basically, see a bad dnd game as a bad movie. You go out of your way to get snacks, sit down and focus on something for a few hours, you get invested in the characters, and then you get dissapointed when it's a shit movie. A simple example of a thing that could make a dnd session not great: Sometimes the characters that players get deeply invested in die for no good reason. Imagine if Luke Skywalker got killed by a random no-name stormtrooper while saving Leia, or imagine the actual ending of GoT.
