All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
You have to know that in Islam it is permissible for a man to take pleasure from his wife as he wishes provided he avoids sex in the anus or during menstruation. As regards oral sex, we do not know any text that prohibits it; however, if he asks you to do so, it seems that you are not obliged to obey him in this matter as this act is contrary to high moral standards and general Islamic decencies in enjoying one's wife.
As regards rubbing his private parts, if he intends to arouse himself and incite his desires then it is a kind of masturbation and you should advise him to this effect, especially that he is doing so in front of the children. Indeed, this might cause bad psychological effects to the children in the future.
Nonetheless, it is not permissible for you to believe without evidence that your husband is masturbating as in principle a Muslim is innocent until he is proven guilty.
With regard to your husband minimizing sexual intercourse with you, you can talk to him and be frank with him on this matter and inform him that you need him. Try to beautify yourself to him and avoid things that might cause him to abstain from you. Additionally, we advise you to contact a medical advisory service and trustworthy sites and explain the situation to them as they might find a solution for your situation.
Allaah knows best.