yeah i can guess fairly well how you feel i had the same problem when my dad left my mom when i was 9 he left for another woman although she didn't have a child of her own but she didn't like me or thats the vibe i got form her she would talk about my mother to me when my dad and brother werent around nasty things to i finly couldn't take it anymore and ended up just not going to see him any more so my advice is some time talk to your dad alone tell him whats bothering you see if you can't work something out try and be calm about it thought as for the dating thing your young yet you could try asking if you can go out on group dates if your parents aren't cool with you going out by yourslef yet but take it from someone who did start dating at 13 wait awhile to go out with guys by yourslef besides thats what school dacnes are for lol. I know it's annoying to be told your to young when you don't feel you are but do you really need the stress of guys yet as i recall 13 was hard eungh with out them lol

sorry forgot to add heres a hug and lots of positive energy for you