Not rttt but didn't want to read your original post OP and forget to come back later.
You can do this. It won't be easy, especially at first. The first few novelty days, weeks, maybe OK. Then it hits this is a new normal and your mind can argue with itself. You can come out the other side, and new ways become new habits done more instinctively.
My rough story is,,, single parent to 2. No help. No friends local. No family support even at a distance. SAHM. In my 40s. Weight crept on. Suddenly I was 2-3 stone overweight but I'm short so that's a lot for me. Never dieted in my life. GP routine health check flagged it up.
It still just played on my mind until I noticed my kids were quite static. Reluctant to go out some days. I had us start couch to 5k. Honestly for them at that point more than me. I'd never have felt able to go out alone and do it. But several wks in they lost interest / got injuries, but I realised I still wanted to go. And I kept it up. Meanwhile several wks in, I noticed I wanted to make slightly different choices. Snack less naughty food. Eat a better breakfast. Watch my portion size. The journey took itself at its own pace but it was happening without a massive conscious decision, just little changes here and there every now & then. But they added up. And as I felt a bit boosted it self-fuelled wanting to take better care a bit more. I'd never have done any of it had I known the bigger picture of changes & effort but it flowed gradually once the first steps were taken. One day at a time. Don't think much further ahead especially in the early days.
As time went on, to avoid injuries, I added in Joe Wicks hiit exercises too. Free ones off his youtube channel. Cost of it: an exercise mat about £10. I do it curtains shut, in my sports bra & knickers (I get v hot lol). Minimal cost. And I can fit in to suit me, whatever the weather is or random free time I have.
It took about 2 yrs to drop from about 11 stone to 8-8.5 stone. I still run 1-3 times a week, between 5-10/15 km a wk (tracked using strava on my phone, nothing extra fancy like sports watches etc). I still do my Joe Wicks as and when.
I'm proud of what I've achieved tho it feels a bit of a cheat as I only set out to be healthier for my kids, to set a good example. Everything else has been a wonderful side product along with massive improvements in my mental health, my confidence, my kids happier to be seen out with me as I look less old (we can even share clothes too & I fit back in old clothes now considered vintage). Some days, some weeks, are tough it's true but I focus on healthy eating snd portion size more than anything, and doing minimum 5k a wk. Many wks that's all I do if the weather or life is against me, and that's OK because this is a long term life change.
One thing which reallllly helped my early days and still now is having an encouraging friend. Mine lives many miles away. But we are connected on strava. And she champions my running achievements. She was running before me, and I never thought I'd match her distances or speeds. But guess what. It happens. And she's told me I inspire her when she's loosing motivation. I have a different mum friend who is my Joe Wicks buddy. We send each other workouts we've done with a quick summary of how it went, was it recommended etc. These things have helped me mentally more than I realised they would to keep going.
Sorry this is long. OP, I truly hope you feel able to take just 1 step. Cos that's a step forward from where you are now. And if you keep doing that you'll travel at your own pace but always heading in the right direction.
One last thing. This might be just me, but for the first few wks I told no one about my goals with the kids or healthy eating changes, looking back it would have felt like extra pressure, being watched. Maybe that's just me but for me, a quiet soft launch was also important to get going. Remember this process is very personal & some people benefit from crowd support holding them accountable. I don't, it's pressure. So have a think what's best for you.
Absolute best of luck. You can do this 100%, and it doesn't need to cost a lot, definitely not gym / club membership etc.