I've just started the gym and protein shakes to try and gain some muscle back.
Weight loss without exercise will result in a higher amount of atrophy which means it will be harder to regain that muscle.
You also have to be eating the right amount of protein for rebuilding muscle which may mean an increase in calorific intake and some weight regain. I think atrophy is inevitable anyway with weight loss as you simply aren't passively carrying around lots of weight all of the time.
It is healthier for your body to be at a lower weight than 110kg, but as is discussed often on the WLI boards, BMI isn't a perfect indicator of a good and healthy weight for everyone.
As we age we also lose skin elasticity.
WLI aren't the solution to weightloss for vanity reasons and we must all accept that our bodies change shape, all the time, and the reality vs expectation can be hard to reconcile with however it is necessary because the fact is you are at a healthier weight now.
I do think there is a lot of talk about uncovering why people eat and resolving those issues without there actually being enough resources or understanding, and a course or 2 of therapy isn't going to resolve everybody's issues with their own personal perception either, but I do think that if the look of your new body is something that bothers you, you should look for solutions.
You can accept that you're at a healthier weight now and celebrate your weight loss achievements and be unhappy about how you feel, either because of how you look or because of the acquired pain from weight loss. The two things do not negate eachother.
It sounds to me like you are aware of the solution for the next step which is to rebuild your strength, and with that it will rebuild your self confidence too.
You just have to be gentle to yourself and understand you've undergone a dramatic transformation and now you owe yourself some sort of rehabilitation to rebuild your strength.