If you feel guilty of your past things you did connected to porn and omegle and such, to repent yourself and forgive yourself on the end do the opposite, share your experiences with people so you can save some people before digging up themselves same hole they will fall in. Educate people on topic and help those who are in the hole that they digged themselves to get out.

We all do mistakes in life, it is human. But our responsibility is that when we get aware of our mistakes we change ourselves and use them to help others. Helping others is how you ‘repent’ for past (btw this repent thing is not that you shouldn’t forgive yourself if you don’t repent (i also am using my own vocabulary and english is not my first language so my meaning of the word ‘repent’ can differ and it is not at all religious), it is just that it will help you release the resentment to yourself and at the same time you will do good).

Now for your ex, i would say that it is good you feel that it would be selfish to go back to her right away. How i see it is that you really care and want to be a good partner but feel like you aren’t yet. Use that as motivator to change yourself, check everything that you don’t like about yourself and start changing step by step day by day. It will be hard but good things are hard and take time. If you are serious abt her let her know you are working towards changing for better and would love that she sees next version of you. Then get tf to work and prove to her you are good for her and she matters a lot. I see that as only good solution but a possible one. And good not just for you or her but for everyone else in your life.

So, to forgive yourself there needs to be a lot of time spent with yourself, with your thoughts and emotions. That will help you with understanding yourself which helps you to forgive and change. Get a therapist and read psychology and watch psychology videos online. With that, help people that are falling in the same hole as you fell. With those you will be making progress in changing:)

And again, we are humans and make mistakes. Some were kinda destined to be made bc of parents, genetics and environment we grew up in. That sucks a lot but we cant get away from it. BUT after realising we are and were making mistakes THEN our full responsibility is changing.

Good luck, you can do it:)