Hello, I am Rafael. Thanks for asking your question - I'm here to support you. (Information posted here is not private or confidential but public).
I am sorry to know about this very frustrating situation.
It is very concerning since after the first year your relationship you have been experiencing a very dysfunctional relationship including constant arguments, infidelity, lack of honesty and respect, which are essential requirements to develop a healthy and fulfilling relationship. Your words show you do not truly share the same needs and expectation sin this relationship, that there is not real mutual trust, intimacy nor understanding between you, and when that's the case, no matter how much you may expect or push each other, the relationship would not work but deteriorate even more with time.
Here is where the significant age difference seems to play a key role setting bigger challenges and distance between you. When couples with big age difference happen to have very good compatibility at their personality level, core values and beliefs, expectations, needs and life styles, then age would not be such a huge challenge, but when the relationship becomes this dysfunctional, big age differences just add extra challenges and problems to relationships.
I invite you to seriously consider getting professional couples counseling in order to work on these core issues and see if you do have what it takes to make your relationship heal and work as a healthy and fulfilling experience, and if not, to work on how you could move on while taking good care of your parental responsibilities. Individual counseling could also help each of you to take better care of yourselves and to better cope with these problems. Does it make sense?