I feel your frustration! But it is a normal part of learning to play guitar.
One reason so many aspiring new guitarist, give up before they ever get to a point where they feel a sense of reward and accomplishment, is that learning guitar involves overcoming several difficult challenges thrown at you all at once in the very beginning.
First you have the pain of tender fingers pressing on steel strings. Then you are using muscles in your hand and fingers that ordinary daily living activities have not helped you to develop the strength required for playing guitar. And, as expressed in your question, you must train your brain to tell your fingers and hands to contort in very unnatural and strange positions to play chords.
My best advice is to abandoned any idea of instant gratification and commit to the idea that learning guitar is a slow process in the beginning. It gets exponentially easier to improve your skills after you get past the huge hurdles you encounter in the beginning.
Think of where you presently are in your journey as merely preparation and training. You are getting in shape to learn to play by developing some basic skills and building finger strength and callouses and coordination. Progress will be very slow in the beginning but if you persevere, you will reach a point where progress comes at a far more rapid pace.
Now to your specific challenge. Before working on transitions between chords, you must first train your brain to tell your fingers to form the proper shape for each of the two chords. Start one at a time. Learn to properly form and play a particular chord (say a C chord for example). Practice forming the chord and releasing your hand and forming the chord again and releasing. Do this over and over until you can go from an open hand position to a C chord without hesitation. Do this before you even think about transitioning from a C chord to something else.
Next step is to learn the next chord (Em for example). Practice forming an Em chord and opening your hand and forming the chord again - until you can play it without hesitation.
Once you are able to form a C chord from an open hand without much hesitation and can do the same with the Em chord, then you can begin to practice the transition between the two chords. To do this, start on one chord, then play the second chord and repeat this process. Start slowly and you will build speed over time. Don't use a metronome in the beginning, it will only add to your frustration. Once you can quickly and easily transition between the two chords, you can begin to practice using a metronome to further ingrain your transition and develop some rhythm at the same time.
It would be very helpful to have a teacher or experienced guitarist, help you with the proper fingering and hand position for every chord you endeavor to learn. Efficiently forming a chord involves more than just putting your fingers on the right strings at the right frets. Each chord requires a different hand position and sometimes arm position. Some chords have you tilting your hand one direction - others the opposite. Some chords have your thumb in the center of the back of the neck, while others may be much easier to play if your thumb is at the top of the neck.
Keep your goals and expectations realistic. It may be helpful to set a goal of learning the I - IV and V chord of a particular key and then learning to transition between those three. In the key of C that would be I = C IV = F and V = G. Once you learn the basic I - IV and V chords and develop the ability to transition between them, you will be able to play literally thousands of songs.
If you accomplish that one small goal, you will develop the passion and desire to continue your journey, which will provide opportunities to continue to learn and improve for the rest of your life. And it gets more enjoyable as you go.
Don't give up! What you are experiencing is normal and something that all of us (who have learned to play guitar) went through in the beginning. It takes slow and deliberate practice to get over the huge wall at the start. It gets much easier after you get over that initial wall. Good luck!
