Lots of things taste good but it’s still fine not to eat them. We can eat other great stuff 
Chocolate is totally keto by the way if you don’t eat the sugary kind.
I try to do carnivore, good thing it turned off my already tiny chocolate addiction…
Can’t you focus on great, very tempting food that is better for you? I may not understand your situation as covid did barely any change to my life and my favorite items are my carnivore staples but I have my moments and I never resist temptation, don’t even want to as it belongs to my core personality.
Practice helps. It doesn’t work always, we should do it when it suits us to some extent but if it’s not too bad and you don’t go crazy due to the restrictions, the more you do your chosen and kind of compatible-with-you woe, the easier it should get. You form new habits, your tastes may change, possibly even your priorities… And in the end you can’t mess it up too often and too much if you try. At least I see that in your life but it’s super slow with my attitude.
If it’s too hard, maybe you can relax your woe or bit. Or make it way stricter, I found the latter works better but sometimes I need my off times too. Needed? Maybe still, it’s fully mental and less and less important. My body is happy with no plants ever, actually.
I don’t know you so can’t guess what are the problematic points for you… You mentioned chocolate and potato chips… Too much carbs (unless you are good with tiny amounts… it can be learned, at least for some of us. I have items I shouldn’t touch but almost any not too processed thing is fine in moderation. our mind is an interesting thing, it can be content with the knowledge and the tiny flavor while saying no could make it rebel…), the sugar in the chocolate is another thing… If you want crunchy things, you can eat cheese whisps or fried bacon too and so many other things, it needn’t to be potato chips. Unless you want potato flavor, that’s tough as only potatoes have it. But if I can live without them (potato was a very beloved staple food of mine for decades), probably you can too.
Chocolate… First I used my homemade chocolate but to me it’s better to forget about it. Not a satiating food so I easily overeat using it… But I always depended on my sweets (at least on vegetarian keto… eating meat is like cheating, it’s zillion times easier and I liked my vegetarian keto. poor me, I knew nothing!) and now I call them desserts when they aren’t sweet… There are so many options! Some people use sweeteners, others use sugar (like fruit, I prefer cream and mascarpone myself, that’s even carnivore, yay. fortunately I am okay with lactose) and well, my latest chocolate was unsweetened (it took years, I kept lowering the amount of sweetener in everything as less and less was perfect to me)… It still was dessert just not sweet at all. It helps if someone likes chocolate because of the cocoa part… But some sweetener is better than giving up and eating sugar galore.
I always considered keto a long term, final woe. Or almost. It changed my attitude and I can be very stubborn and my very strong inner hedonist self always searches for ways to get everything it wants. I don’t (can’t) do sacrifices in my eating. But you can eat great stuff on keto. It was actually too indulgent for me, I had to go stricter and I must say extreme low-carb is WAY easier than my old keto (even if I would add meat). Because the carbs messed things up. One should choose their carbs well, it’s very individual which kind and what amount we can handle well.
You did keto for a long while, right? You know you can do it again. Most of us have harder times. Oh I had a whole carby summer after keto once. Well, low-carb (my previous woe) but still, too carby. Some days surely was quite carby, I have a fruit garden and fruits are awesome even if unneeded. I went off keto hundreds of times. But I kept practicing my keto and my older, low-carb habits, I kept changing… It was easy for me as high-carb was over when I went low-carb. Occasional days happens but I always run back to low-carb as it’s way better, more enjoyable. And I am a hedonist so yep, I stay low-carb for life.
So I just try and if I go off, I come back almost right away. And I rarely mess it up epically.
And I am no comfort eater but the best food is very low-carb anyway. It’s not hedonistic to eat sugar and feeling bad at all, why people do that? Not like I didn’t need MANY years to stop doing it occasionally but regularly… Stupid decades old habits. They often die hard. In my case, they didn’t even die until I ate lots of carbs (mostly vegetables).
Sorry, I had thoughts and wrote them.
Good luck! If you have some specific problem, tell us, maybe we can help. What is exactly where you mess it up? Can’t you eat something else in that situation? For many of us, being hungry and stressed is almost a hopeless situation. Eating some proper food first may help a lot!
Of course, don’t feel too bad. Most of us aren’t perfect regarding how we eat. We are humans.
You didn’t mess everything up. You surely have your little keto muscles 
I become a horrible new person (well, old…) if I let too much carbs into my life but I stop and in no time I look like a disciplined one while I am anything but 
I just want the right things and don’t want the bad ones. For a while, but that’s not a bad start. And it gets better with time.
For some of us, changes take a lot of time and effort and off times.
