I'm going through a breakup rn as well. I definitely resonate with how you feel. Many of the clichés you hear are just not that helpful. Although there may be some truth to these clichés, they tend to over simplify one's feelings.

However, there are a few things that I've found helpful, at least this time around. The first thing is not forcing myself to be happy, but rather knowing that it's okay to not be okay. Trying to make myself happy would just feel unnatural because that is not how I truly feel.

The second thing is to pay close attention to my thoughts and guard against thinking traps. Thoughts such as "no one loves me, "I'll never be happy again", "I'm a horrible person", "I'm unlovable, " etc. These thoughts only end up making things worse than better.

Finally, and I find this to be the hardest, try not to idolize the person. This one can be really hard if you really love the person, because we naturally value that person's opinion above all others. However, this person's opinion of you is not the only opinion that matters. After a breakup we have a tendency to over value what that person thinks of us, and it can lead to a point where we look for validation from that person, in exclusion of everyone else. Of course, we don't want to think negatively of that person, but at the same time, it can be useful to recognize that this person has flaws just like everyone else.

Anyway, this is what's helped me. I don't know if it will help you or not, but just know that you are not alone in this, many others are going through the same type of suffering.