How can I get over the fact my boyfriend cheated?
As you have said that you are still with your boyfriend, you must love him a great deal and want to work through the fact that you are struggling to trust him. As you do love him so much, it is also understandable that you still feel anger and jealousy, if not I would presume that you no longer cared for him. However, the fact that you even describe yourself as 'obsessed' by the huge age difference, means that you need to deal with these issues if your relationship if ever truly going to be back on track and move on.
Whenever someone cheats, their partner always feels like there is something wrong with them or that they are lacking something and that is why their partner cheated. That is just not true! People cheat for all sorts of reasons all their own and it has nothing to do with not getting what they want from their partner. They might be unhappy in the relationship and be looking for ways to finish it, but the blame for this can't be attributed to the innocent party. They cheat because they are insecure, bored, angry, or just greedy, but it is not because of you and what you do. Normally if an affair leads to a break up, if both parties are honest, there were probably many issues with the relationship, and the fact that someone else came along and presented a different opportunity, was just a case of timing, chances are at another time, she wouldn't have even registered on his radar.
I love him but I dont trust him after he cheated with a younger woman?
Does it really matter that she is younger? Isn't the issue more that he cheated? Full stop. Maybe getting hung up on this one fact so that you feel you are justified in being annoyed? You are justified, totally. It is possible that it just happened to be a younger woman, as your husband said it has nothing to do with age. Would you be comfortable if he cheated on you with an older woman? I think that would be really upset. You were 33, which is still young! I don't think your husband cheated on you because he wanted a younger girl. It can be anyone. If you are not bothered with the cheating, then it definitely possible that you could move on from this.
You could go to counselling together so that he could explain what it is that drove him to have the affair and you could learn together how he can help rebuild your trust in him, as this is something he needs to deal with too. You are already doing what you can to cope day to day. If you don't deal with this issue now, it will eat away at your relationship from the inside out.
If you are not sure if your spouse is cheating, take a look at our short video on 7 Signs that your Spouse is Cheating!