Mate shit happens. Nobody's perfect. I once backed into a bollard and I've even parked so close to my garage door that it was concave until someone pointed it out to me then I moved the car back. We have all done dumb things. All of us.

For me, it helps to pretend that the "me" that made the mistake is my friend. Would I say the things I say to myself, to my friend? No.

I wouldn't say to my friend "you're the worst", "I hate you", "why are you so bad at everything", etc, if they made a mistake or felt bad about something. So why would I treat myself like that?

It takes practice, patience, and self-love and self-kindness. Self-reflection and introspection are difficult, but constant reaffirming is needed to rewire the neuron paths that make us sad. Our brains enjoy a well-used path, and the more it uses those paths the harder it is to break. But you can rewire it, by recognising those thoughts and paths, and consciously saying "i am not bad, I am human and that is okay!"

I'm not always kind to myself, but I'm getting better. Try to learn from what happened, and always try to be kind to yourself. It is okay, it will get better, I am here supporting and rooting for you. 💜💜💜

Hardly anything matters 🤷‍♂️

think about worst case scenario and plan B based on that

Aaarrggghhh, one of the big issues. And there ain't no easy answer. And sooner or later we all end up in this situation.
Step 1 - be aware of what you've done. Tick.

Step 2 - apologise to all that have been impacted by your actions. Identify the harms done and who to. This bit can be brutal to one's self-esteem. Step 3 - rectify the problem where possible. Fix what's broken.
Step 4 - atone - this can get problematical. As atonement may mean a permanent change in behaviour/attitude etc.
Step 5 - forgiveness. This is the really hard one. But if Steps 2, 3 and 4 above have been done in full, on time and within budget, then possible. Particularly of self. Forgiveness from other people is usually easier to obtain. Step 6 - Ongoing awareness of triggers that may lead to a relapse. Also, you only get a limited number of Steps 1-6 before you get written off as incurable and/or irredeemable, so it's worth plugging the triggers into your ongoing awareness.
Optional Step 7 - was it your problem or were you lured into it by another for their own personal reasons? Only ask this after you've run out of repeat scripts.
All the above is provided on a 'for what it's worth" basis.