It can really depend where you live so I think the first advise is to take it easy on yourself.

• It is ok to combine ways of transports, say cycle to the first train/bus then load the bike on it/park at the station
• Start with a sturdier bike, the one which is bigger and more visible in traffic and gives you a better sense of control.
• don't expect cars to respect you because you cycle or to know what to do around you. Bad drivers are everywhere. Don't try to prove points. Safety is more important than ego.
• get yourself a good, large backpack. This will be your new back seat
• Take taxi/uber when needed. I once arrived to a friend's wedding held out of town in a taxi and literally everybody I knew there looked at me as I was either a fool or a millioner. The bill was like 35$. Way cheaper than owning a car.

Lastly, enjoy how good you will feel. Climate protection and all that is great but your body will love you for it and you will feel it. Good luck

Download your local bus system's shitty app and learn how to work it.

At the stage you're at, open communication is important. Tell the car you need a little space and go stay with a friend for a few nights.

You should probably mention the general area you live in for actual recommendations. Like I'd suggest public transport, but I know it's god awful in the USA and might not be an option for you if you live there.

You haven't mentioned public transport yet, so if there is any in your area I would have a look at what it might be able to do for you.

If you have a public transit system you can use Google maps to tell you exactly where to go and how to get there, including bus transfers. Unfortunately it does not show how far away the bus is like the transit app does, but it is better at communicating when I have to leave and how long I have to get to my stop.

Don’t be afraid to use a car if you have to. Reducing car dependency is great, but if you live in a place without proper infrastructure it can be almost impossible to completely ditch your car. In that case I’d suggest becoming active in local politics to try to improve the situation.

Have you tried crawling, jogging, skipping, running, roller skates/blades, skateboard/scooter, skiing, ice skates, surfing, or swimming?

Learn your most used routes and start optimising

My girlfriend came off her scooter, seriously fucked up her arm and hasn't been able to pass medical to get her licence back and also sold her car.

I'm not sure I'd recommend it for everyone, but it's worked for her.

Starting with safety tips: wear bright colours (safety vest), helmet and ensure lights are installed for night riding. Especially if you're an ebike user, have a secure lock and secure your bike every time when it leaves your sight on a trip.

Review your local transit authority's policy on bikes (are there racks for bikes on buses, are they allowed on trains during rush hour, can you bring them on island ferries etc.) Being able to transit then cycle the rest of the way will be a low cost way to get to places you imagined were only accessible by car.

Is there a carshare program in your town? For those occasional times you may need one to bring home a new bookshelf or travel in a group of 4 somewhere far, or want to hit up a bike trail somewhere that public transit is completely nonexistent, using carshare is beneficial and costs much less than car ownership.