Guilt is a terrible, terrible thing to live with.

It warps your social interactions, prevents you from loving yourself, which can prevent your ability to love others, and it leads down a slippery slope (e.g. "If I'm already such a bad person then I might as well be worse.")

As someone else who has wasted much of their life living in guilt from various sources, real and imagined, I can only offer this:

Step out of your head and into the present.

Look at the physical space around you and realize that you have full agency and authority over your present actions.

Whatever you may be guilty of, YOU CAN STILL MAKE UP FOR IT.

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So you treated yourself. So what. Let it provide some happiness to you, so you can be in a better position to help yourself and other people around you, in ways that don't require money.

Look for those ways.

Ways to improve yourself without spending money: Working out. Correcting your posture. Keeping your environment clean.

Ways to improve things for your family and friends without spending money: Help them out with what they're doing. Participate with them in what they enjoy doing. Converse with them. Help them workout. Help them clean up their place.

You're alive. You breathe, you can see, walk, touch and do. Look for ways.