I don't like my reactive dog anymore

I know this sounds wrong. I got him when he was 10 weeks old, i raised him, got through puppy blues, he was alright and got along with other dogs well. He's the kind of dog who wants to play with every dog there is.. but at 1 1/4 years or so he started fighting because of toys in the dog park. He started being reactive towards dogs - only on the leash. At first only towards bigger dogs but now any dog no matter how small, but the reaction is worse when it comes to big dogs. He himself weighs 42kg. I know he's not scared and i'm not sure if it's because he wants to play. I also don't think it's aggression.

I'm at a point where i've really started to dislike him even though he's a sweetheart at home and towards humans, he's just very energetic but it's like I've lost all feelings for him and i feel horrible. I've tried a personal trainer but trainers really are expensive and i don't believe there is anything that could help... I'm thinking about rehoming him every day but my boyfriend is against it. We can't go anywhere because he'll just go crazy when a dog walks past and embarrass us. I feel like my life is over because the only places i can go to is where there are no people around.. i really did everything to be a good parent, i trained so much with him but once we're outside everything seems forgotten or useless.

I don't know where we went wrong but i regret getting him every day. He really loves us and is happiest with us but he just makes me miserable.. still my boyfriend won't allow to give him away and i would feel bad if we did but it's really affecting my mental health

I guess i'm just posting this to get it off my chest but please don't tell me what a horrible person i am i already feel like one and i don't need strangers agreeing...