How to create a device with a processor: sources of information?

Question

Iron

There is such task:
To make the device.

The temperature sensor measures... Temperature!
The measurement data (voltage, as I understand it) comes to the processor, which decides whether to let the current from an external source further down the circuit or break the circuit.

a simple program is embedded in the processor:
If TEMP=50 and TEMP>50
then [break the circuit]
else [do nothing *]

*that is, the device for closing / breaking the circuit in the whip state initially, for

example have experience in creating such devices:
Advise a plan (naturally preferably step-by-step, a-la instructions) of what should be studied (specific books, sources, etc.) and where you can find practical instructions for building such devices - so that I don’t even have such questions when they arise such a task

PS , as you can see from the text and wording, I am quite far from the topic of creating such devices, (that's why I am writing here in the hope of finding an adequate and caring person)
Therefore, any sufficiently detailed answer will be unrealistically useful

Thank you,

UPD:
To everyone who answered, thanks for time spent:
One for trying to help,
Others for trying to "open their eyes": to say that something is beyond someone's strength. If your experience tells you that something is not given to you, well, let it remain so for you. Everyone lives in their own illusions, in which it is more convenient for them. I turned and wrote to Habr, as to a community where you can find pros in their field: pros in creating pieces of iron, in this case. I know that it is difficult, but possible, to find a multi-skill person who is capable not only of being a professional in the glands, but also of teaching other people. Habr is an excellent field for such a search.

Again I turn to those who are ready to help.
1) About Arduino. I'm familiar with arduino. Familiarized that the programming of their HIS microcontroller is carried out through their environment. The offer is excellent for a person who was simply given such a task: to make a piece of iron, and so that it would be as fast and efficient as possible.
But this option is not for me, in my question I proposed the task of creating just such a device based on the skills that I am going to have ( programming microcontrollers, working with sensors and servos, creating the simplest robots - devices with logical operations based on input data from others pieces of iron ... And other skills that I am not yet able to present due to my little experience in this area ).
Therefore, if anyone can suggest sources of information (including English), where you can start to master these skills:
Tell me, please.

2) Those who advise using a thermostat, because its capabilities are enough for such a task - I approve, understand, and highly appreciate this approach. He obviously comes to mind first when solving such a problem, so Thank you! I think if someone comes to this discussion with a similar problem, your answer will definitely help him.
But for me, this approach in solving the problem is not suitable. As I said above:

in my question, I proposed the task of creating just such a device based on the skills that I am going to have (programming microcontrollers, working with sensors and servos, creating the simplest robots - devices with logical operations based on input data from other pieces of iron ... And other skills , which I can’t even imagine due to my little experience in this area).
Therefore, if anyone can suggest sources of information (including English), where you can start to master these skills:
Tell me, please.

UPD2:
Thanks to Vladimir and Evgeny (_lm) for the material and answers.
If you have anything else to add, write, I will be glad to read it.

Answer 1

Here, in my opinion, it is generally possible to do without processors, and without controllers. Google threshold temperature sensor at least. Or a thermostat. Or a thermal fuse - self-healing or not.
See what exactly you need.
In general, under this condition:

if TEMP=50 and TEMP>50
then [разорвать цепь]
else [ничего не делать*]

You can generally do without all this - it still won’t work, because the condition is impossible

Answer 2

Maybe this? https://arduinomaster.ru/datchiki-arduino/arduino-...

Answer 3

It is easier and more reliable to buy a thermostat. Same SQ0832-0020