First, it's important to realize that it was likely an accidental and embarrassing situation for both you and your mom. Try to focus on the fact that it was a momentary thing. You can start by talking to a close and trusted friend about how you feel, just to get it off your chest.
Just pretend it never happened. Avoid thinking about it consciously. Every time the thought pops up, quickly shift your focus to something else.
You could try to find humor in it in a very private way. For example, think about how it was just a crazy, unexpected moment. But again, don't share this humor with anyone else. Also, remind yourself that it was an accident and that everyone has embarrassing moments sometimes. This can help you feel less awkward about it.
If you saw a friend's nude stories, it's a very sensitive situation. First, respect their privacy. Don't spread or gossip about it. You could consider talking to your friend privately and sincerely, let them know how you came across it accidentally, and apologize if they feel violated.
A good way to cope is to change your perspective. Instead of seeing it as a horror story, see it as an opportunity. Maybe it's a chance for you to realize how far you've come since the relationship ended. You can also take this as a sign to be more selective in your swiping. Don't settle for someone who reminds you of your ex or who might cause similar problems. Focus on finding someone who truly makes you happy and brings out the best in you.
First, accept that it's a normal human behavior, even though it was a shock to see your mom doing it. Talk to a close friend about how you feel, but make sure it's someone you can trust to keep it confidential. Also, remind yourself that your mom is a person with her own needs. As time passes, the shock will lessen, and you can start to view the situation more objectively.
If you accidentally see your sister nude, the first thing is to respect her privacy. Immediately look away and give her the space to cover up. Then, it's important to act as if it didn't happen in a sense. Don't bring it up in a way that makes her feel embarrassed or uncomfortable.
First, you should give yourself some time to process your feelings. Don't react immediately. Then, when you're calmer, have an open and honest conversation with your girlfriend. Let her know how you felt when you saw what you saw.
Take some time for yourself first. Go for a walk, listen to music, just to calm down. Then, when you're ready, you can think about having a conversation with your mom. But don't rush into it. You need to be in a relatively calm state of mind.
One way to cope is to write down your feelings. You can keep a journal and write all the things that make you hate her and the sad parts. This can help you get it out of your system. Then you can think more clearly about how to deal with it.
First, give yourself time to grieve. It's a process. Try to remember the good times with your mom. Maybe write about your memories or create something in her honor. Also, consider seeking professional counseling if it gets too overwhelming.